The Galena Century Radio (GCR) Crystal Detector Diode/Crystal Switch – Kit is the same unit designed for the GCR A-Runner and GCR J-Walker Crystal Radios to enable switching radio operation between galena crystal and diode. The kit is all brass and will fit the GCR Control Panel – 2 x 10 Point, the GCR Control Panel Dual System, or can be integrated into a radio of your own design.