Part Number: 8.751-237.0-KAR Cross Reference Part Number(s): 87512370 This 18 mm Karcher Ceramic Plunger Sleeve Kit includes ONE (1) each of the following: 18mm ceramic piston sleeve, plunger bolt, o-ring and copper spacer. Please purchase three (3) kits to replace all ceramic pistons in a Karcher pump. Ceramic piston (plunger) sleeves can sometimes break or crack and require immediate replacement before causing further damage within the pump head. Broken shards of ceramic can damage the pump seals and pump manifold and can flow through the system causing damage to the unloader, hose, trigger gun, or clog a spray tip nozzle. Identification of broken or cracked ceramic plunger sleeves can be difficult, however one sign to look for is milky or caramel colored pump oil, which indicates water has entered the pump body and mixed with the pump oil. See Additional Information for a list of compatible pumps.