<p> <b>USA Standard Sizes Chart</b><br> 2.0mm = B = 1<br> 2.5mm = C = 2<br> 3.0mm = D = 3<br> 3.5 mm = E = 4<br> 4 mm = G = 6<br> 4.5 mm = 7<br> 5 mm = H = 8<br> 5.5 mm = I = 9<br> 6 mm = J = 10</p>