I have a set of main tune and band spread knobs that go to the following. S-38A, S-38B, S-40, S-40A, S-52, S-53, S-76, SX-43 and SX-71. These are the knobs with the silver ring insert. Both of these knobs are near mint shape and show no signs of wear. I only have the one set. $30.00 plus shipping. Regards, Gary