Material: Super Elastic NITI. Type: Round. 0.012 upper; 0.012 lower. 0.014 upper; 0.014 lower. 0.016 upper; 0.016 lower. 0.018 upper; 0.018 lower. 0.020 upper; 0.020 lower. We strive to exceed all your expectations and put a smile on your face.