90521-ZW1-B00 Gear (0.50) Shim D - Overview. The 90521-ZW1-B00 Gear (0.50) Shim D is a precision-engineered component essential for Honda marine engine systems. This 0.50mm thick gear shim supports the marine propulsion system by ensuring accurate gear spacing and alignment, which is critical for smooth operation and longevity. Crafted to exact factory specifications, the shim ensures seamless integration with existing parts, maintaining optimal performance and durability.. Key Features. Precisi