Some puts umbrella sells like was on some fords but I don't have a number. Perfect circle made some with a Teflon wiper but the valve guides needed cut down to install them. May be the same as the sealed power you mention. Trying this set on a 350 head that will install without machining. Has a metal jacket with rubber inside that will fit without turning the guide OD down. Just measured the guide OD and looked up applications that listed stem size and ID of the big end. Then made sure they would clear the springs. Was afraid they may be to much oil control, but so far so good. Haven't used long term enough to determine the end result though. Guides were still in spec but on the edge of the high side.