The Mahle OE plain ring set is specified as Performance Steel Napier second rings at 3.942 in bore diameter with a 1.0 mm section and .136 in radial width, offered in a 48-piece bulk pack. These plain second rings are supplied for engine rebuilds and commercial use where that exact sizing and plain ring form are required, allowing engine builders to match precise bore and ring section specifications.
Mahle Rings Perf Steel Napier 2nd Ring 3.942in x 1.0MM .136in RW Plain Ring Set (48 Qty Bulk Pack)