You gain two more square donuts with this expansion pack. Try buying a different color to create your own custom look. One expansion pack plus the original Boner Kit will give you four square donuts total. Super stretchable yet firm Thermoplastic Rubber TPR. Stackable and compatible with the Boner Kit. Product dimensions ball ring exterior 1.3 inches by 1.3 inches. Ball ring interior .9 inch by .9 inch.