This replacement piston ring, 1.5 mm thick, made by the DS brand, is made of highly durable cast iron with excellent heat-conducting and sealing properties. It is intended for the first undersize of cylinder boring (on standard 38 mm models) or as the factory standard for newer engine types. As a reliable and long-lasting replacement, it ensures high compression, prevents loss of engine power under load and efficiently removes heat from the piston crown, extending the working life of the whole assembly. Ring diameter: 39 mm Ring thickness: 1.5 mm Ring profile: Standard rectangular profile Manufacturer: DS (high-quality replacement part) Compatible models: Tomos mopeds with A3 and A35 engines: Automatik A 3 (75-85), Automatik A 35 (89-), A 5 Colibri (89-) Newer generations of Tomos mopeds: Flexer 50, Sprint 50 (2004-), Targa 50, Youngster 50, Revival 50 Tomos APN series: Models with the cylinder bored to the first undersize (Ø39) Before fitting the new ring, be sure to thoroughly clean the grooves on the piston of all carbon, soot and baked-on oil residue so that the ring can move freely. The material is brittle, so fit the ring carefully, without excessive or sudden spreading over the piston crown. Before sliding the cylinder on, lightly coat the inside of the cylinder and the ring itself with clean two-stroke oil for a safe first start and to prevent dry friction. Stock and availability of parts can be checked by sending an inquiry or by calling our phone number.