Liberator collar--any experiences?

Somewhere I heard about the "Liberator" collar (from Australia). Their website describes it as having an alarm which is "activated by the characteristic leap of a cat as it launches itself at a bird."

I'm wondering whether anyone has used one and whether it helped stemmed the bringing of prey into the house. (It's not the dead "presents" I object to--it's the live mice etc. that are let loose in the house!)

Thanks.