15cm to 30cm. The length of casings produced by each family is different. The longer the sausage, the longer the casing. There are three kinds of casings: large, medium and small. If the casing is too big, the sausage poured out is also very big, which is not refreshing to eat, and it is also very troublesome to pack it too small. Therefore, it is best to choose no. Casing and15cm to 30cm.