This is a small, circular disc that the deodorant balm sits on.
Material: Also typically made of polypropylene (PP) or sometimes high-density polyethylene (HDPE).
Function: It sits on top of the threaded column inside the tube. As the knob is twisted, the platform is pushed upward, raising the product out of the tube. Its diameter is just slightly smaller than the inner diameter of the tube to create a seal that prevents the balm from slipping down but allows it to move smoothly upwards.
Seal: In many designs, the platform has a lipped or gasketed edge to create a better seal against the inner wall of the tube, preventing the soft balm from leaking down into the mechanism.