90560-ZV5-821 Spring (4Mm) Washer - Overview. The 90560-ZV5-821 Spring (4Mm) Washer is a finely engineered component specifically designed for Honda marine engine systems. This 4mm spring washer plays a vital role in providing tension and securing assembly points, contributing to the reliable operation of your marine engine. Crafted to meet Honda's exacting factory specifications, it ensures seamless integration with existing parts, maintaining optimal performance and durability.. Key Features.