Like some of the others, I use canvas. It will hold scent longer and better than any of the other bumpers. I have also recently begun using the Dokken pheasant, quail and grouse trainers (just to see...) and the dogs really seem to like them. I work brits, though, and play retrieving only goes so far with them. Once they get bored with it, I just move on. And we haven't lost a bird in years.