This 12-piece key set from Kreator contains ring keys in different sizes. They are made of sturdy satin chrome vanadium steel. Loosening or tightening nuts and bolts is no problem at all. The deeply curved rings ensure better power transmission. Dimensions of the ring spanners: 6 x 7 / 8 x 9 / 10 x 11 / 12 x 13 / 14 x 15 / 16 x 17 / 18 x 19 / 20 x 22 / 21 x 23 / 24 x 27 / 25 x 28 / 30 x 32 mm