Redman CB NMO Mount Connector Rubber gasket washer Rain Cap seal Antenna Stud

The footprint wasn't quite large enough to be useful for my setup which is a Comet SBB-5NMO on an NMO mount through the roof of my Tahoe. As soon as I actually tighten down the antenna the collar just pushes this gasket out of the way, and makes it basically useless. If your antenna has thicker material at the collar it might work with this gasket, wasn't the case for me.