For all Yamaha watercraft/jet ski models with a 1.8L engine Excellent for high-boost applications. Eliminates flex in cylinder wall. CNC machined out of as solid block of lightweight T6 6061 Aluminum Anodized, high quality, and durable Made in the USA Our block guards have been meticulously designed and are CNC machined out of as solid block of lightweight T6 6061 aircraft grade aluminum. The block guard's function is to support and eliminate flex in the cylinder walls. Our block guards feature a corrosion-resistant anodized coating and cooling ports to allow proper coolant flow through the engine thus preventing hot spots throughout the cylinder. Made in the United States. Applications: Fits all Yamaha watercraft/jet ski with 1.8L engines