Hey sideoftheroad you needed to make no explanation to that rude responder in post #8 who had nothing to contribute and apparently seldom does other than contempt for this website.
I do hope I contributed also and by the way The Great planes plastic with the alum backplate that 52Larry mentioned and the CB alum backplate plastics that Scaleonly linked are much preferable over the all plastic types. This is because there is less of the problem of the backplate deforming during tightening and there is groved capture ring in the alum backplates.
John