Ferei  filters for headlamp HL50II:

Especially suited for

Easy to attach, easy to remove.
Fix the filter with Ferei silicon rubber case on the head of HL50II, the headlamps will produce a beam light. 

Yellow filter produces a warm beam, which has a better penetration in foggy weather.

Red light is commonly used to help to preserve night vision and also reduces the probability of alerting game animals, which generally do not pick up red light as well.

Green light additionally helps people with enhanced visual acuity as our eyes are more receptive to green light.