I have 3 of these, 3" OD, 1.5" ID, 1" thick. I can see the steel laminations where the paint chipped off of one of them. They are also heavy Are these of any use for RF? I'm converting an SB-220 to 160 and thought about one of these for the tank circuit till I saw the core. Now I'm not sure. Thanks & 73, Jim WE4S Get BlueMail for Android