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Thread: REVIEW: Nitecore MT21C Adjustable Head Flashlight

  1. #1

    Default REVIEW: Nitecore MT21C Adjustable Head Flashlight

    The Nitecore MT21C is a new light from Nitecore featuring an adjustable, right-angle head. It can function like a traditional flashlight with the head angled forward or it can be adjusted to multiple angles to project light in a different direction. It uses a single 18650 battery (or two CR123A batteries) and XP-L emitter to achieve about 1000 lumens and 185 meters of throw.

    The MT21C head adjusts to 5 different positions from straight to right.

    Here are the key specifications as tested:

    Skip to the commentary section at bottom to read my subjective notes on the MT21C.

    Disclaimer: This light was provided at no cost by Nitecore Store, shipping from their location in Texas. Nitecore Store is an authorized Nitecore distributor for the U.S.A. Retail price at the time of this review was $59.95.


    The MH23 arrived in the traditional black and yellow Nitecore retail box.

    The rear:

    Possible uses on one side:

    Drawing attention to the 90 degree right-angle feature on the other side:

    Inside the box, a plastic tray holds the MT21C, pocket clip, holster, lanyard, spare o-rings, warranty card, and manual.


    The manual is in 10 languages (English, Spanish, German, French, Russian, Japanese, Chinese, Italian, Romanian, and Korean); each language’s section is complete as the text is quite small.

    It is online here:
    Nitecore backs the MT21C with a 5-year warranty.


    The defining features of the MT21C are the adjustable head and metal hanging loop.

    Nitecore lists the length at 131 mm, head width at 25.4 mm, body width at 25.4 mm, and weight at 103.5 g. My measurements confirmed the dimensions within a half mm; weight as tested was slightly higher at 106 g.

    For a size comparison, here is the MT21C with other flashlights (and the batteries they use).
    L to R: Nitecore TM03 (18650), Olight R50 Pro (26650), Fenix E15 (CR123A), Nitecore MT22C (18650), Nitecore MT21C (18650), Manker E11 (AA), Nitecore SRT9 (18650*2), Jetbeam T6 (18650*4).

    Starting at the front, the head has a black bezel and fairly shallow, smooth reflector. The reflector was free of any imperfections with only faint machining marks. Typical for Nitecore, the bezel is not removable by hand.

    The lens is AR-coated. The XP-L HD V6 LED is centered using a black centering disc.

    On one side of the head is a HOT warning – aligned directly above the switch. A metal loop on the head allows the MT21C to be suspended from a hook or string. The loop can be removed, though doing this repeatedly would reduce the tension holding it in place from both sides. The hanging loop and flat spots below the switch prevent rolling when the light is placed on a flat surface.

    The opposite side of the head has the serial number (not pictured).

    The head can be adjusted to one of five different angles; a ball plunger and detent hold the head at the chosen angle. Some of these detents are visible in the picture below. The MT21C’s hinge arrived over-lubricated – better than under-lubricated, but a bit messy.

    The switch is an aluminum circle surrounded by a ring that illuminates to display voltage and indicate a low battery.

    The battery tube has fine diamond-pattern knurling – consistent with other Nitecore models. On one side is the Nitecore logo and web address.

    On the other side is the model number, registration, and disposal information.

    The tail is completely flat – making for easy tail-standing. Note that there is no lanyard hole on the tail; the lanyard must be attached to the hanging loop or pocket clip.

    The tail magnet is strong enough to hold the light securely on ferrous surfaces. Combined with the adjustable-angle head, this makes it useful in a variety of situations – whether on the underside of a car hood, or in this case, on a refrigerator door.

    The MT21C disassembles into three pieces – head, battery tube, and tail cap. The threads are longer on tail end of the battery tube than on the head end. Threads at both ends are anodized, so locking out the light mechanically is possible by unscrewing either the head or tail cap slightly.

    Those threads are square cut and well-lubricated at both ends – just as one would like to see!

    Inside, the head end has a single solid post. There is no physical reverse-polarity protection (it does have electronic protection) – meaning both flat top and button top batteries are compatible.

    The tail has a single gold-colored spring. The spring and battery tube length had no problem accommodating lengthy protected cells.


    Pocket Clip
    The MT21C’s pocket clip is reversible; the light can be carried head-down or head-up in pocket. This offers flexibility; the lens can be protected in pocket (head down) or clipped to a hat (head up). The clip holds to the MT21C very securely.

    The lanyard is of good quality with a neoprene wrist strap, adjustable cinch, and tight-knit rope for looping around the hanging loop.

    The holster is the same quality holster design that accompanies many other Nitecore lights. A hook-and-loop flap keeps the MT21C secure, either head up or head down. A d-ring, belt loop, and hook-and-loop flap on the back provide multiple carry options.


    The XP-L HD V6 and smooth, shallow reflector produce a sharp hotspot and wide spill.

    Tint & Temperature
    The color and CCT are not specified by Nitecore. I found the hotspot was neutral (about 4600K) with a slightly yellow tint. The spill was cool (about 6500K) and blue tinted. Overall, it’s a pretty common tint combination for high-output, cool XP-L emitters.

    To demonstrate the overall color balance, here is the MT21C surrounded by lights with emitters of various tints and temperatures. Camera W/B set to daylight.
    L to R: Convoy S2+ (4500K XM-L2 T6 4C), Nitecore MT22C (XP-L HD V6), Nitecore MT21C (XP-L HD V6), Convoy S2+ (6500K XM-L2 U2 1B), BLF348 (219B SW50 R9050), Lumintop Tool Cu (4000K 219B).

    Note: Nitecore used a 3500mAh 18650 for the official specifications. Two (2) CR123 or RCR123/16340 cells could also be used. I tested runtime with a Nitecore 3400mAh NL1834 18650. Ambient temperature was 70F +/- 3F. Higher outputs were achieved using Samsung 30Q flat top batteries. Nitecore’s Advanced Temperature Regulation (ATR) means real-world performance will vary some based on conditions.

    Turbo is rated for 1000 lumens and 1 hour – and Nitecore states that the 1000 lumens is prior to temperature regulation kicking in. The MT21C has Nitecore’s Advanced Temperature Regulation (ATR); ATR adjusts the output based on temperature rather than time.

    At 30 seconds, output was measured at 998 lumens with the 30Q cell and 919 lumens with the 30Q – ever so slightly below the rated specification. Under 80mm PC fan cooling and with the NL1834 cell, the MT21C dropped had a mostly linear output drop over time. 10% of original output (ANSI testing standard) was reached at 2:13 – over twice the rated runtime. The side switch was blinking rapidly from about 1:55 into the test onward through when the test was terminated at the 9-hour mark.

    High is rated at 400 lumens for 3:45. I measured 483 lumens with the NL1834 and 480 lumens with the 30Q cell. With the NL1834, output was nearly flat until stepping down about 25 minutes into the test. It then held flat past the 3 hour mark. 10% output was reached at 3:31 – nearly matching the rated runtime. The MT21C was still providing about 1 lumen when the test was stopped after more than 5 hours; as observed with the Turbo test, the MT21C will hold on with a low output for quite some time.

    Medium is rated at 190 lumens for 7:30. I measured 226 with the NL1834 and 222 with the 30Q cell at 30 seconds. Output was very flat until rising and falling starting at 6:28. 10% output was reached at 7:12 – also just shy of the rated runtime. Given the slightly smaller cell used for testing (3400mAh vs 3500mAh), Nitecore’s rating is fair.

    Low is rated at 50 lumens for 25 hours. Output was tested at 58 lumens with both cells and was flat for over 26.5 hours. 10% output was eventually hit at 27:12 – exceeding the rated runtime.

    Ultralow is rated at 1 lumen for 700 hours. Output was tested at 1.3 lumens with both cells. Runtime was not tested.

    All output levels:

    All runtimes tested:

    Amperage Draw
    As measured with a fully-charged Nitecore NL1834:
    • Turbo: 2.45A
    • High: 1.05A
    • Med: 0.43A
    • Low: 114mA
    • Ultralow: 4.2mA steady, occasional blip to 7.8mA

    I tested throw distance at 1.46 meters and the resulting candela was 8718 at 30 seconds - equivalent to 187 meters of throw. This closely matches Nitecore’s specifications of 8500 Cd and 184 meters of throw.

    Nitecore advertises the MT21C as constant current – and I found no signs of any PWM during testing.

    Parasitic Drain
    The switch is electronic, so some parasitic drain is to be expected. What I found interesting is that it would rest at 12µA yet every 7 or 8 seconds jump to 4mA less than a second every before returning to the lower level. For this reason, a true measurement was not obtained.

    Low Voltage Battery Protection
    The MT21C powered off only when the battery’s protection circuit kicked in at 2.5V. The MT21C does not appear to have any low voltage cutoff of its own, though the rapidly flashing side switch LED and diminished output would let a user know the battery was low before risking damaging the cell. Still, this is not a light to set somewhere and forget about if using an unprotected cell.

    Impact Resistance
    Nitecore rates the MH23’s impact resistance at 1 meter. This was not tested.

    Outdoor Beamshots

    All photos taken with a Canon SD4000IS camera. 1/4" exposure, ISO800, Daylight white balance, F2.0. Approximate distances: White deck railing @ 15 ft., white fence in distance @ 75 ft, back of dock @110 ft. Conditions were clear.


    (not pictured; no impact relative to control)






    The MT21C has 5 regular output modes, 3 special modes (Strobe/SOS/Beacon), no mode memory, but direct access to Ultralow and Turbo.

    From off:
    • Press once to perform a battery voltage check
    • Press and hold about 1s to access Ultralow
    • Press and hold about 2.5s to access Turbo
    • Triple press to access Strobe

    From on:
    • Press to cycle upward through modes (Ultralow->Low->Medium->High->Turbo)
    • Triple press quickly to access Strobe
      • Press to cycle special modes (Strobe->Beacon->SOS)

    • Press and hold about 1s to turn off


    No problems were experienced with the Nitecore MT21C while testing.


    The MT21C is an extremely versatile light thanks to the adjustable head, magnetic tail, hanging loop, and reversible pocket clip. The adjustable angle head might seem like a gimmick to some, but it is really useful in many situations. The pocket clip can be attached to a jacket and the head angled to make the MT21C function similar to a headlamp. The magnet and adjustable head can put light where it’s needed under a car hood. In one real-world use, I laid the MT21C on a deck railing with the head angled down over a cooler – providing light just where it was needed.

    The 1000 lumen output isn’t anything special for 2018, nor is the tint, but the runtime and output ratings Nitecore provides are honest. The lumen bump from 1.3 lumens on Ultralow to 58 lumens (as tested) on Low is pretty significant; it’s a minor item but I would have preferred Low to be around 30 lumens. The hold-to-turn-on and hold-to-turn-off interface takes a little getting used to – as does the lack of mode memory – but the direct access to both Ultralow and Turbo is very convenient.

    I’m satisfied with the overall quality and the smaller details – like the threads being square cut and o-rings and threads being properly lubricated. The reflector is clean, the lens is anti-reflective, there is no PWM and either button top or flat top cells can be used. The voltage indicator (which truncates, rather than rounds) provides a great way to check battery health and the SOS/Beacon modes provide a safety option should that be needed.

    All in all, the MT21C is a versatile, jack-of-all-trades light that’s a respectable value.

    Lux Meter: Dr. Meter LX1330B
    Integrating "sphere": Homebuilt tube-style device calibrated on other known lights and test results. Numbers should be considered relative to each other and my other review figures but accuracy is in no way certified or guaranteed.

    Camera: Canon SD4000IS
    Micrometer: Mitutoyo CD-6ASX
    Multimeter: Craftsman 82170

    Last edited by Bdm82; 05-07-2018 at 09:57 PM.

  2. #2

    Default Re: REVIEW: Nitecore MT21C Adjustable Head Flashlight

    Updated to include an animated gif showing all 5 angles that the head adjusts to.

  3. #3
    Join Date
    Dec 2007

    Default Re: REVIEW: Nitecore MT21C Adjustable Head Flashlight

    Thanks for the review. Shame Nitecore rarely offers NW or CRI emitters these days, because I like a lot of their lights and UIs.

    This is also an interesting take on the adjustable-head lights from the likes of Klarus and Rofis. I can't help but think, however, that a hinged head like this is an obvious point of early failure. Short of taking the thing totally apart, do you have any idea how the electrical connection is made between the head and body?
    Last edited by pipspeak; 05-08-2018 at 02:47 PM.
    MH20GT - LX2 - QuarkAA - H52w - H501w - MagLEDs galore - Former E1B/E2DL/6P/120P/D10/L2D/L1D/M3/DMini/McGizmo owner (love the Marketplace)

  4. #4

    Default Re: REVIEW: Nitecore MT21C Adjustable Head Flashlight

    Lovely lamp and excellent, very detailed review !

    I'd certainly acquire this lamp if it were available in AA version.

  5. #5
    Flashaholic* old4570's Avatar
    Join Date
    Feb 2009
    Melbourne - Australia

    Default Re: REVIEW: Nitecore MT21C Adjustable Head Flashlight

    No wires that I can see ..
    So might be passing current VIA the hinge and ball indent ?

  6. #6

    Default Re: REVIEW: Nitecore MT21C Adjustable Head Flashlight

    Thanks for the review. How is the hinge holding up on this light? Does the head still stay in the chosen angle during use, or does it move unintentionally?

    These are on sale now, so I'm tempted.

    I prefer the hinged approach to angle adjustment, rather than rotating the head.

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