This ring sizer has 63 sizes on one large ring. They are marked with sizes a-z, with 2 rings in each size, and 1-6, which are the equivalent of sizes 13-15 in half sizes (2 rings in each size) . A-z are the sizes used in the u.k. Starting with us size 0.5 being "size a", size 1 is uk size "b", and so on, until you get to size 12.5, which is uk size "z". Each letter measures a half-step.* Sizes A-z And 1-6 In Uk Sizes * Eqivalent Of Sizes 0-15, Us * Each Size In In Half-steps * 63 Rings In All * 2 Rings In Each Size