Bridgewerks MAGNUM 20SRS SPEEDOMETER MODEL - 20 amps. Bridgewerks has always been known for extraordinary innovation - pioneering products nobody else can build. Once more, we are proud to offer an exciting new product you won't find anywhere else! With the Bridgewerks speedometer, you can monitor your train speeds constantly, not just when the train passes a marker on the track. This is a fantastic product for the true model railroad enthusiast!