Polish knacker (knockwurst, knacker sausage) is highly seasoned scalded sausage made from beef, pork, and fatty tissue similar to a frankfurter, but shorter and thicker.
While Bratwurst is made out of both finely minced pork and beef and wrapped up in a sausage casing, knacker sausage is made out of mainly pork, veal, and flavored with garlic. The color of knacker sausage also tends to be a more reddish or orange tint, rather than the pinkish color that bratwurst displays.