Size #56 SUPER HEAVY DUTY Grinder replacement knife. Fits Butcher Boy #56 commercial meat grinders. It is solid Stainless Steel and fully resharpenable. This knife weighs 50% more than a standard stainless swirl knife. The blades are 4 5/8 tip-to-tip. Center square hole is approx. They will fit your unit if your plates are approx 5 1/8 across. Fits Biro, Hobart, Berkel and other very heavy duty meat grinders. Always within 24 hours.