This is a new in the package Piston Rings set (1 set of rings for all 4  pistons!) for the 1977-1982 GS550 models.  This is a standard size (STD) ring set which is correct replacement for 56mm Standard bore pistons.   Correct replacement for #12140-47031.    Each of the 4 rings sets has the 2 compression rings and the lower 3pc oil control rings for the pistons, everything to get your pistons/ engine running nicely again.   Get your old bike up and running again. We only sell the best! This is a top-quality aftermarket item shipped new in the package.  Good stuff if you are riding or restoring or  racing these cool bikes. This is correct for these models :