1Applicable Model: The motor piston ring is for Mariner outboard 2?Stroke 20 to 25HP outboard 15HP 20HP 25HP. Please confirm whether it is consistent with the product you want before buying to avoid unnecessary return. 2OE Number: The part number for reference is 39?827491A12. Please confirm whether it is consistent with the OE you need to avoid wrong buying and other problems. 3Durable Material: The outboard motor piston ring is made of durable and reliable cast iron material, high strength and wear resistant, having long service time. 4Improved Engine Efficiency: The outboard piston ring Std helps to maintain optimum engine performance by providing a tight seal between the piston and cylinder, preventing oil leakage, reducing friction and heat generation. 5Easy Installation: This marine piston ring is easy to install, and doesn't require any complicated tools, perfectly fitting for ensuring seamless performance.