Looking for a compact, no hassle battery solution for your retractable stock M4? This kit has everything you need to and will eliminate problems like tangled wires and cumbersom battery compartments. This kit is made for rear-wired M4s and replaces the buffer tube with a full metal buffer tube that easily stores the included 7.4v LiPO battery. Included with the kit are deans connectors which can optionally be installed for better connectivity between the battery and the motor. The included battery comes with a small tamiya plug and requires a LiPO charger to charge.