Comes as pictured no ring. Piston is 36mm so on a stock 28mm stroke crank with a 36mm head it will be 28.5cc. Need the 36mm head and ring to complete the upgrade on a stock 26cc engine. The baja sold here is 26cc so this head with the stock crank is a 28.5cc engine or add a 30mm crank for a 30.5cc stroker engine. Fair quality piston.