We bought 12 tractor trailer loads of motorcycle parts inventory from Dixie International / Dixie Distributing when they liquidated their entire inventory. You are purchasing 100 sets of rings; enough to do 100 engines, off of the pallet that you see in the pictures. The part # on the box is #P17551R .010. As you can see in the pictures, we found that part number in an old Dixie Distributing  catalog. That part number is for a 1972 and later Harley-Davidson Sportster.  According to our parts manager, "later" means it only goes up to 1983. These rings are for iron head Sportster engines. In 1984 they came out with a redesigned piston that superseded this and used a different ring. These rings are .010 oversize bore size of 3 3/16.