[Barry_R]

The top ring determines the hone finish. The vast majority of second rings are cast iron - its the right material for that position.

Sealed Power and Speed-Pro are divisions of the same corporation - Federal-Mogul. If the box says Speed-Pro - - you have Speed-Pro rings. The Speed-Pro line uses only ductile iron base material and a plasma-moly face coatings (except for the Hellfire stuff).

Most standard replacement Sealed Power rings are on a cast iron base with a standard moly coating (may or may not be plasma applied depending on the manufacturing plant).

Roughly 50% of Sealed Power and Speed-Pro rings are actually manufactured in Dana/Perfect Circle (soon to be Mahle) plants under contract. Quite a few Perfect Circle rings are manufactured in Federal-Mogul plants. Big business works that way.