We have tried all sorts of them for tracking bear and none of them really worked well. I still swear the best light for tracking blood is a kerosene lantern. Something about that lantern light really makes blood show/glisten, trouble is one good bump and its all over.
I bought one when they came out and was excited to try it out! boy was I dissapointed! I now use a product called blue star A forensic blood detection product that law enforcement uses to find blood at crime scenes.www.bluestar-forensic.com/ or http://bloodglow.com/
I can’t seem to figure out how to post the link to these! sorry you will have to copy and paste