pretty sure metal clad seals without the rubber on the guide skirt area are to be used with a sealer. At least that's the way I've used them. white Teflon is my favorite when you can use them. Usually when using triple spring I use the metal clad w/ blue rubber inside the guide skirt and a .500 guide outside dia. There are blue rubber metal clads, that look like the Comps that don't have the rubber in the guide area.