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., Battery: One AA size NiMH, lithium or alkaline battery. Panasonic Eneloop or Eneloop Pro is highly recommended. Batteries are not included in the box., Automatic stepping down from High to Medium, and from Medium to Low when battery capacity is low, Smart user interface provides fast and easy access to all brightness levels and beacon-strobes., Durable electronic soft-touch switch, Precision machined unibody casing from premium grade aluminum bar stocks, Proprietary heat sinking design bonds the LED board directly to the unibody aluminum casing, Durable natural hard anodized finish (Type III Class I), Battery reverse polarity protection, Preinstalled bezel down pocket clip, Battery power can be disconnected by slightly unscrewing the tailcap to prevent unwanted activations or parasitic drain, Waterproof to IPX7 (2 meters, 30 minutes), Ouput on HIgh: H1 475 Lm (3min, then 352lm, total 0.5 hr) or H2 352 Lm (0.9 hr) / 236 Lm (1.5 hrs) / 144 Lm (2.8 hrs), Output on Medium: M1 79 Lm (4.9 hrs) or M2 40 Lm (9.6 hrs) / 18 Lm (21 hrs) / 7.4 Lm (48 hrs)