SF L1 -Dual stage light, Low 1.1 Lumens, High 22 Lumens.press for momentary light, turn for constant on, uses primary batteries only. Length 4.60 Inches.
SF Claimed runtime on primaries-90 Hours on low, 4 Hours on High.
SF E1L- Single stage output, 25 Lumens on primaries,30 Lumens on Li-Ions, Press for momentary, press harder for constant. Length 4.0 Inches.
SF Claimed runtime on primaries-4 Hours.
Note, The E1L uses a KL1 Head that can be used on the E-Series Lights from Surefire,this includes from 1X123 up to 3x123 batteries, The L1's head can NOT be used on any other lights.
I used to use a dual stage cap on my E1L, then when i switched to rechargeable Li-Ions, i went back to solo stage switch and use a pop on and off diffuser on the end that doubles as a lens cap,if i want low light i leave it one, otherwise i remove for full blast.
Other Surefire masters will pop in an add to this i am sure, it coms down to preference really, it is Up to You.
Peace
IF