The Mercuric is a light that pushes light weight, small size, and power to the upper limits. The poly carbonate body and aluminum head help keep the weight down, and durability up. The CREE XM-L T6 we are using pushes the Mercuric to an output of approximately 700 lumens. To turn on, or off simply turn the head of the light, no magnetic switches, or push buttons to fail. The Mercuric has a high quality reflector which achieves an 18 degree beam with a relatively large spill over, making the Mercuric ideal for recreational diving or a backup light for the techies. We have placed a good hard attach point on the rear for those that wish to attach a bolt snap. Packaged with 2 x CR123A batteries to get you started out of the box right away