i assume you have the dmd & mfu. if you just need the battle unit (apple) mount with wiring harness, so you can switch your battle unit from one tank to another, Tamiya has them for about $37 as noted by others the whole battle unit (apple, mount, firing led and attached wiring cost $75 & up. Imapct also sells a compatible battle unit system and also sells the mount as a separate item. The impact and Tamiya systems are fully battle compatible but they use a different plug from the apple to the mount.