This bracelet mandrel is great to measure bracelets or bangles. The circumference can measure 10cm - 25cm (4 inches to 10 inches). Simply place the bracelet or bangle onto the bracelet mandrel and read the size. For reference the diameter measurements are 3.18cm - 7.96cm (1.3 inches to 3.1 inches). The bracelet mandrel is a must have for any workshop. It is also handy for customers to be able to measure their own bracelet or bangle so they can buy another in the same size.