Material: 304 Stainless Steel Inner Diameter: 35mm /1.34" (fixed size) Height of Rings: 30mm ( 1.2" ) for 450g Ring 40mm ( 1.6" ) for 560g Ring 60mm ( 2.36”) for 830g Ring 2 kind of closing way,magnet closing and screw closing. Magnet closing is more convenient when wearing but it may pinch the ball skin if you don’t pay attention on it,as you can imagine,the magnet is strong,when 2 half pieces close to each other,the closing is quick and you need to hold your ball skin completely inside the ring to prevent pinching. So there is another closing way,screw closing for selection.