Thread measuring set Packed in leatherette case Consists of 16 sets of 3 stainless steel wires. Consists of 16 sets of 3 stainless steel wires.3 inches long, accurate to tolerance of plus or minus 0.001".Supplied in handy leatherette case with chart showing dimensions for measuring threads 40 to 3 TPI.Metric Order No.: 600-0600Inch Order No.: 600-0050