I have not had the pleasure of hearing one of Uncle Jay's Power Play units, but I'd bet on it being effective. Since other brands have been mentioned in this discussion, I have been using the Sceery special coaxer for years, fastened to my rifle with a special fastener which is part elastic, part velcro. It has more of a chattering sound than any of the other types I have heard and is very effective in coaxing a coyote right on in. Very simple to operate with one finger on my left hand. I really don't think it is meant to copy a lip squeak though.