check out the bowgrunter plus by away hunting products, its awesome!! I have used the primos grunters without success but last season I had a buck dancing under my tree with the bowgrunter, he was so upset!! The grunt tube pins to your shirt or jacket and there is a rubber tube that runs up to your mouth that pins to your collar and when you inhale it grunts, you can grunt while at full draw with this set up....it is far and away the best grunt call I have ever used.