The BCR looks like a 9 volt battery, works like a 9 volt battery, but doesn't act like a 9 volt battery.It fits in your 9 volt battery holder and connects to the 9 volt battery clip. There are no extra wires to deal with, no modification necessary on any engine. This device allows you to store or display your engines and never need to charge your battery to operate them. After one minute of applying power, at 10 volts or more, to activate the BCR, the engine will be able to fully operate. No longer do you have to replace the battery or be concerned about the battery leaking and damaging your engine. The BCR can be left in the engine indefinitely. After turning the power off to the track, the BCR will hold a charge for 2 to 3 hours, depending on the engine. If you have not operated the engine in 2 to 3 hours, power up the engine in the reset position, for one minute at 10 volts or more. Your satisfaction is my goal, so please ask any questions you may have before you bid. , 100% POSITIVE feedback! Williams AUTHORIZED DEALER since 1994. MEMBER TCA 87-26695 Be sure to add me to your favorites list !Check out my other items !