I worked on a game ranch a few summers ago that had them... but I wasnt really all that impressed with them. They may work in some situations but that hasnt been my experience with them. I'd say not worth the money

My Gerber Carnivore (original model) is a good flashlight - better be for the price. Bright white light, pistol grip, and tight sheath. The blue/red LEDs work nicely for getting around in the dark. Tracking a deer through fallen autumn leaves last October, I kept toggling between the white and red/blue lights. I preferred the bright white. Perhaps the new model and the Primos work better for tracking blood.

I used my primos tracking light and it picks up blood pretty good it does pick it up better than a regular light.