Our nut is made of tungsten steel, high hardness and high quality, competitive rice. Nut is used with tool parts, like tool holders, screws. Here are some detail specifications, also we can make special nuts according to your demands. ER11(A,M type), ER16(A,M type), ER20(A,M type), ER25, ER32, ER40 and OZ25. If you need these nuts, please contact us at any time! Nut