Sold on Amazon Genuine Original Equipment Manufacturer (OEM) parts! This piston and ring kit (part number 25-874-13-S) is for lawn and garden equipment engines. Piston and ring kit 25-874-13-S includes the piston that compresses the fuel and air mixture inside the cylinder before ignition and the rings that seal the gap between the piston and the cylinder wall. Wear work gloves to protect your hands when installing this part. For Kohler.