[Jack21]

Ditto the above about Total Seal bringing out a gapless ring that goes in the top ring grove. They might even have a web site.

The other manufacturer of gapless rings that I'm aware of is Childs & Albert. Might look them up also.

Almost sprung for a set in my own engine. They are supposed to increase engine vacuum to the extent that some folks install restrictor orifices in their PCV line.

The major advantage, as I understand it, is that as the rings wear with mileage, the gapless feature maintains the ring seal, whereas a conventional 1 piece ring gap opens up allowing blowby.

Might be a good question to ask, "Howcome the automakers don't use them?" The automakers don't use roller rocker arms either.