https://www.graysonstoys.com/product/tiger-water-bottle-mbp-z05b-h-mbp-a050c-dedicated-replacement-parts-inner-stopper-gray/
Tiger Water Bottle MBP-Z05B-H MBP-A050C Dedicated Replacement Parts, Inner Stopper, Gray - Graysons...
Size: 2.1 x 2.1 x 1.7 inches (5.4 x 5.4 x 4 Weight: 1.0 lbs (0.044 kg) Stopper: Polypropylene