Hello IMightBeWrong,
My first post to you...
Elzetta offers four types of tailcaps for their ZFL flashlights.
1) Rotary tailcap: this one functions the exact same way as a classic SureFire 6P twisty tailcap. You press the tailcap for momentary; for constant on you have to twist clockwise. This is a 1-level switch (HIGH only).
2) Clicky tailcap: this is a standard 'forward clicky' (click-on/click-off tailcap). Press halfway for momentary. Push more for constant on. This is also a 1-level switch (HIGH-only).
3) High/Low: the high/low switch is kind of a combination between the 'clicky tailcap' and the 'rotary'. When the tailcap is completely turned clockwise (so it can't turn any more) it is in the 'HIGH' position. Press half-way for momentary-high; press more until it clicks for constant-on-high. If you want 'LOW', you twist the tailcap slightly counterclockwise. On low it functions as on high: press half-way for momentary; press more until it clicks for constant-on.
4) High/Strobe: this tailcap works the exact same way as the High/Low, with this difference that the low function is replaced by a strobe.
You can find a good video on the Elzetta website, showing the difference between the High/Low and High/Strobe switch: Elzetta.com - Products & Faq - Elzetta ZFL-M60 - Elzetta High/Strobe Tailcap Demonstration. (Edit: I saw that Coyote302 already provided this link)
Regards,
Nachtwacht.