The O2 BEAM was developed specifically for long distance lighting and this model features a green light. Green light is best for low light conditions, because the human eye recognizes the color green faster than other colors. Also perfect for hunting, as some game cannot see green light. The mount with this light fits (20mm-32.5mm) barrel and scope diameters, and adjusts, tighten and locks without tools.
Specifications:

Type
Output	40/400 Lumens
Bulb Type
Body Diameter
OAL	6.25"
Weight	1 lb
Battery	18650 Li-ion Rechargeable
Proofs	Impact/Water Resistant
Color	Black Anodized
Material	Aluminum
Head Diameter	2.13"
For Series
Rechargeable	Yes
Filter Color	Green
Switch Type	Pressure Pad