Collagen Casings take the place of using natural hog or sheep casings. They can be used for fresh or smoked sausages. They are made from beef protein. There is no preparation necessary. Just put them on your stuffing tube and before you know it, you will have uniformly sized sausages! 17mm are snack stick size. (Remember you will need a 1/2" O.D. tube or smaller for these.)