LED: Cree XM-L2 Cool White (Nominal CCT 6300K). User Selectable Levels: 3 main levels (High, Medium and Low). Each main level can be programmed to one of its two sub-levels. The second sub-level of the each main levels can be further programmed to different brightness levels. Light Output (runtimes) – High: H1 456 Lm (PID, approx 1.4 hr) or H2 250 Lm (1.6 hrs) / 102 Lm (4.1 hrs), Medium: M1 50 Lm (11 hrs) or M2 22 Lm (26 hrs) / 8.5 Lm (70 hrs), Low: L1 2.5 Lm (8 days) or L2 0.38 Lm (38 days) / 0.05 Lm (2.5 months) / 0.01 Lm (3 months), Beacon Strobe Mode: 0.2Hz Beacon at Low / 0.2Hz Beacon at H1 / 4Hz Strobe at H1 / 19Hz Strobe at H1. Light output are ANSI out the front (OTF) values. Runtimes tested (and parasitic drain estimated) using Panasonic CR123A batteries. Operating Voltage Range: 2.7V – 4.2V. Battery: One CR123A or 3.6/3.7V 16340 li-ion rechargeable. Batteries are not included in the box. Parasitic Drain: Negligible (much less than the self discharging of a battery). Beam Type: Floody beam from frosted lens, with 90 degree beam spread. Dimensions – Head Diameter: 0.9 inch (22.8 mm), Length: 2.7 inch (68.6 mm). Weight: 1.16 oz (33 gram). Features: PID thermal regulated output at the H1 level, Battery capacity indicator (LED flashes 1-4 times, 4 short clicks to start), Automatic stepping down from High to Medium, and from Medium to Low when battery capacity is low, Builtin over-discharging protection, Durable electronic soft-touch switch, Smart user interface provides fast and easy access to all brightness levels and beacon-strobes, Durable natural hard anodized finish (Type III Class I), Sealed and potted LED driver circuitry, Battery reverse polarity protection, Tempered optical grade glass, Orange peel textured reflector, Waterproof to IPX7 (2 meters, 30 minutes).