P15d-30 cap. The base is 15 mm diameter. The ring is 30 mm diameter. There are 2 contacts. Plated metal and the bottom has epoxy very rugged. For old vintage and classic cars, tractors and motorcycles. The base and contacts are solder-able for long life. The reason this product is a NCNRNW non cancellable, non returnable because the socket is old and corroded and causes the disc to break. CE and Rohs.