Durston Tool’s PrecisionFit™ technology is the most accurate ring sizing system in the World, guaranteed to provide a perfect sizing between mandrels and rings. The USA’s favourite ring mandrel range, with over 20,000 sold in the USA in 2019 already! PrecisionFit™ is the leading ring sizing system globally, used by individual jewellers through to large, multiple chains. Don’t settle for less than PrecisionFit™.