The Fusion 400 is a small light with all the big light features. The big light features include adjustable beam angle 12 ̊ » 100 ̊, pressure safety valve, 4-way visual battery charge indicator (green = full • yellow = half • red = low), and removable head all in a small package with a 400 lumen output. This light is a great backup or as your companion during the day to poke into holes or under a ledge. The Fusion 400 is a must for any diver. Includes lanyard, 14500 Li-ion battery, charger, USB cable and padded case. Accepts either AA alkaline batteries (not included) or Lithium-ion rechargeable battery. Only use 2 AA batteries with the extension piece, DO NOT use 2 x 14500 batteries with this piece. Key Features: Light meets American National Standards; Institute (ANSI) FL1 standards; Use with both lithium-ion and alkaline batteries; 400 lumen output; Adjustable 12 degree (narrow beam) to 100-degree beam angle (wide beam); 100%, 50%, 30% power level; Emergency strobe.