NITECORE RSW2DRSW2D( no longer encompass flashlight) Remote switch. Suitable for: P12GTS, MH12GTS, MH25GTS. FITS FLASHLIGHTS WITH A TAIL DIAMETER OF 1" (26mm) AND A DOUBLE LAYERED TUBE Capable of getting entry to STROBE READY™ and changing brightness levels to boot momentary-on and constant-on illumination. How to Use? Constant On: Short press Button A or B Off: Short press any button Brightness Adjustment: Press and maintain Button A. Release to select the current level. STROBE READY™: Press and keep Button B. Release to come back to the former status. Momentary On: Press and hold Button C. Release to expose it off.