Material: Nickel titanium Round Stlye Nature Form. 0.12 Upper, 0.12 Lower 0.14 Upper, 0.14 Lower 0.16 Upper, 0.16 Lower 0.18 Upper, 0.18 Lower 0.20 Upper, 0.20 Lower. The natural curvature of the arch wire is closer to oral cavity space, which will save the doctor's time. 10 Pieces/Pack Please note the size in your order, or we will deliver randomly.