This Blue-White Industries 72000-550 is a Retrofit Kit for A-100N Series Peristaltic Pump this kit allows new style A-100N tube assembly to retro-fit into older style pump head. Ships with qty 1 Clear Cover (71000-156) and qty 1 Adhesive Spacer Pad (90012-399). Place adhesive pad onto the inlet and outlet side of the pump head. The pad helps to secure new style tubes (model A1-1T, A1-2T, A1-3T, A1-4T, A1-5T, A1-6T, A1-7T and A1-8T) in the pump head. Kit ships with further instructions.