"The AIS3000 can be attached to External Battery Frames in order to increase the runtime.The maximum number of External Battery Frames is limited to 4 due to the recharge time.There are 2 different External Battery Frame models depending on whether the frame has Circuit Breaker integrated or not. 2-External Battery Frames for AIS3000XR Frames with Circuit Breaker: ISVTBXR2B6SISVTBXR6B6SXR Frames without Circuit Breaker: ISVTXR2B6SISVTXR6B6S "