This listing is for twenty pieces. The PN weld nut features a strong single button projection which gives a deeper, more penetrating weld than is ordinarily obtained from other types of projections. Thus, the PN is ideal for use with heavier gage material. Thread Size 5/16-18 Width (in) 5/8" Thickness (in) 9/64" Length (in) 63/64" Hole In Sheet (in) 0.375