I bought this to fit a lipo alarm in the Hurricane as Luke's video said its not possible to do so without this. There are two problems with this product:
(1) Its a pain to get on and off and requires a hex wench to do so. The stock bottom part this replaces stays on perfectly without a screw and comes on and off easily
(2) I found this is not even needed. If you get the Tattu 450 mAh 3s lipo with JST connector (55*30.5*16mm) and put a JST connector on the Hurricane and use the mini lipo alarm (sold on out of darts) then you can easily fit the battery and lipo alarm in the gun without this extension (make sure to take the large clear plastic piece off the balance connector on the battery or it won't fit).
fits great too