I've seen these advertised on tv and have also seen ralph and vicki cianciarulo?from archers choiceuse these. Does anyone have any info on them? Are they just a gimmick?

i have a set of the extreme shrink fletch i love them, if you buy watch the video that somes with. mine had a video make sure you put into water slow as it shrinks onto shaft. other then that i have shot these many times and lasted longer then normal fletchings.. thats my .02