Provides the necessary electrical isolation between the Xtrema Charger and your balancer while providing a fully integrated balance charging system. One BIM allows you to connect up to two Xtrema Balancers to the Xtrema Charger. You must have at least one BIM connected to the Xtrema even if you only have one balancer connected. Comes with two 10 Pin ribbon cables that connect to charger and balancer. An additional cable is needed if you use a second balancer.