New UV rated plastic cup used between the DuraBalloon® and the DuraStem to help support the balloon. Made to be run over and still able to be used…You can't break it…With your hands at least. 4" Diameter.   If you have Bobber or Bobber Maxx you will need the upper cup screw*  Screws are sold separately.  Call our customer service team to place your order if needing the upper cup screw.   We are here to help.  800.332.8730