The Traxxas TRX-4 doesn't come with the largest electronics box, it doesn't take much to run out of room. I had switched to a Spektrum 6 channel receiver which was too wide for the factory box so I widened this one on the inside by 4mm. I also made the inside twice as tall as the factory box. This should use the factory box covers, both for the wires and the top of the box as well as the factory gasket and screws. The foam for the wires can be carefully removed from the old box and I just used some 3M double sided tape to tape it down in the new box. the foam should also fit pretty much perfectly. I suggest drilling out the holes a little bit for the screws as I made the holes slightly undersized. other then that it should be an exact replacement. I don't guarantee that this is 100% waterproof, but it should be pretty close to the factory box. I haven't fully submerged this in water or anything.