The Arrma Kraton Bumper spring tends to break often and you must buy the full Bumper set to get this part. Print it with 100% infill and never change it again.
Note*** TPU tends to shrink. For the overture TPU I scaled it up by 1%. This was enough to compensate for any shrinkage.
Note #2*** I made this for a friend and it is untested. If you need it to have more support/Strength just let me know and I will fix it.