We are often asked why a 1” square punch can not be used in place of a 1” round punch when using the same coupling nut. Unlike the diameter of a round punch, the diagonal dimension of a square, rectangle or hex punch is measured like a television screen–from corner to opposite corner. If the diagonal dimension of your shaped punch exceeds the body diameter as it would in our 1” example, the punch would not fit through the bore of your coupling nut and therefore can not be used.