Note that this chain ring is placed on the chain finger and the underside of the ring is designed to be comfortable for the hand.The chain ring is designed in four sizesSizes include the following:United States: 7United States: 7 1/2United States: 7 1/4United States: 7 3/4These designs are ready for 3D printing ...The 3D file of each size is placed separately and as a compressed file.Contact me for the desired size and model ...