TKR1726 – Piston Pin Retainers (21aP/21bM/21aM, 2pcs) Piston pin retainer clips (wrist pin clips) for the Blok 21aP, 21bM, and 21aM engines. Package Contents 2ea Piston Pin Retainer Clips 21817010 This item is not eligible for Tekno general warranty program.