Here we have a great item! This is 2 new sets ( enough for 1 engine) of Standard STD. size piston rings for the  now vintage Kawasaki KZ305 and models made in 1981 1982 1983 and 1987 1988.  This is also correct for European made Z305 CSR bikes from 1988 This has the 2 compression rings for both pistons and the lower oil control rings. These are top quality aftermarket item. The rings fit perfectly the stock, Standard size pison for the KZ305 from these years. These are correct replacement for Kawasaki part # 13008-1008.