The Galena Century Radio (GCR) Rotary Switch 1 x 10 Point – Base is the same unit designed for the GCR A-Runner and GCR J-Walker Loose Coupler Crystal Radios. The Rotary Switch face measures 3.96” in Diameter. The 1/2” x 3” backing plug is designed to slip into a 3” Diameter ABS or PVC Pipe. The base has been milled so it can be fitted with brass as desired and can serve as an integral part of a crystal radio of your own design.