This is a new in the package standard size 52mm (STD) Piston Ring Set  (this is a complete ring set for All 4 Pistons!) for the  1980 1981 1982 1983 Kawasaki KZ400J DOHC engine motorcycle.  This was a 4 cylinder 400cc model mainly for the European market.   This has the 2 compression rings and the lower 3pc oil control rings for all 4 pistons, everything to get your pistons/ engine running nicely again.   We only sell the best! This is a top-quality aftermarket item shipped new in the package.  Correct for part # 13008-1005.  If you have a twin cylinder earlier year KZ400 these will not fit..but we do have KZ400 Twin rings on the website for your bike. Good stuff if you are riding or restoring your bike.