90501-ZZ5-M01 Washer Plain (5Mm) - Overview. The 90501-ZZ5-M01 Washer Plain (5Mm) is an essential component within Honda marine engine systems. This simple, flat washer functions to distribute bolt or screw loads evenly, preventing damage to mating surfaces during assembly. It plays a crucial role in maintaining the structural integrity and longevity of the rigging and hardware systems, ensuring components stay securely fastened under various marine operating conditions. Designed according to Ho