Exact Fit ring sizers in US sizes 7 - 17. Variations in ring width will often entail a minor change in sizing. These high quality sizers are available in standard widths of 4mm, 6mm, 8mm, and 10mm to take the guess work out of sizing for specific widths. They are also precisely matched in profile to comfort fit cores, which are now an industry standard. A cable to hold the set is provided free of charge when a full set is ordered. Please allow snug clearance over the relevant knuckle when sizing. Sizers are made from durable and high quality Delrin.