i made my own once. i didnt use a colar or anything to turn it on..i just turned it on and nocked it. worked great shooting targets and stuff. the fit in the nock was very snug. shot a buck this year and watched it fly and hit...it went out..i was like great! a pass through! nope...i hit the backbone or shoulder and he snapped my arrow off and took the head and 3 inches of shaft. never found the light..it wasnt in my nock or shaft..even at dark i never found it..i guess with a colar i wouldnt had that problem lol..but for how invaluble they are when hunting i think ill just come up with some cash and buy good ones..