INCH FASTENERS

Most popular in the United States and Canada, inch fasteners follow a naming convention that lists diameter, number of threads per inch, and length in terms of inches. Ironically, these fasteners are generally expressed as whole numbers for smaller sizes and as fractions for larger sizes. Metric bolts and screws represent diameter and thread pitch or length in millimeters, often followed by abbreviated letters to indicate the fastener’s material. Unlike inch fasteners, which express screw thread reciprocally, large numbers in metric fasteners indicate a coarser thread.