This decoder is made to fit the Life Like HO Scale SW9/SW1200 switcher. Easy installation exactly replaces the existing PC board in the locomotive. No need to remove the weight. The decoder provides a means to install a white LED or 12 Volt bulb as headlight. Because the 1.5 Volt rear light in this locomotive is difficult to replace we provide a dropping resistor right on the decoder. Three function outputs. Size: 0.100" thick - fits P2K SW8/SW9/SW1200.