This design allows you to mod your Nerf Rapidstrike without destroying the original battery housing. Simply print it, install the blank 2.5mm copper wires to fit in the designated slots and solder the contraplug to it. Attach the plug from the lipo to the contraplug and you are ready to go (uh.... Shoot!!) If your Nerf is equiped with stock flywheel motors use a 2S LiPo, if your Nerf is 'upgraded' with 12V motors you can use a 3S LiPo.