The Clover Thimble is designed to protect your finger from accidental pokes with hand needles. Protect & Grip Small- This thimble has a rubber body and a metal tip. The rubber body has a scalloped design for air flow, keeping your finger cooler and the metal tip is dimpled and ridged to allow pressure when pushing the needle. Packaging has a hole/size guide. Inner diameter approximately 14.5mm(9/16 inch).