Edible Collagen Casings take the place of using natural hog or sheep casings. There is no preparation necessary; just put them on your stuffing tube and before you know it, you will have uniformly sized sausages. Use the 32mm casings for Brats or Italian sausage. Smoked casings are recommended if you are going to be smoking your sausage. Fresh casings are recommended if you are going to be grilling or frying your sausage.