4" overall. Tailcap switch. Water resistant. Impact resistant. Strobe. CREE XPL LED. Memory retention feature. High: (500 lumens, 1h 10m runtime), Low (50 lumens, 3h 55m runtime). Includes M-LOK and Keymod adapter with remote on/off button with cord. Remote button includes hook and loop mounting straps and double stick tape. Aluminum body. Crenulated head for self defense. Requires (1) CR123A battery (included). Clam packed.