I have two. One of the originals and a nitralon type. One is plastic and one is alluminum. They both work very well and the batteries last approx. 1 hour of run time. I have a blue filter which only makes the blood appear black. I'm not sure how much it helps. The lights are compact and are very bright for their size though. Buy the batteries from Surefire. One case of 12 for 15$. These same batteries cost 4-6$ a piece in the store.

You might want to consider the new lights from Browning at Cabela's. They have the same power for much less cost. My friend bought one and it is very nice. He bought one with LED's and a 65 Lumen light for what I paid for one plain 65 lumen light from Surefire. The LED's will light up your trail and last hours and hours while saving the bright light for lighting up whole areas. Have fun.