Hastings, 3-1/2" bore piston ring set. Chr/Moly. +.020"

Std cyl. bore: 3.4980" (88.85 mm).
1st. ring: 1.6mm.
2nd ring: 1.6mm.
oil ring: 4.0mm.

Tech tip: Piston grooves vs piston rings.
It's not difficult to determine if a Hastings piston ring set will fit a certain piston. You should measure the height of the piston groove in the piston itself. The 2 top grooves will be for compression rings, the lower groove will be for the oil ring. In most cases Hastings oil rings are of the low tension 3-piece flex vent type. Ring heights are listed for reference.
Tech tip: Piston oversizes.
For each oversize cylinder diameter will increase with .010" (0.254mm). The standard bore of the cylinder is listed for reference.
(Information provided by Hastings Manufacturing Company, Inc.).