SCREW PITCH GAGE SET UNIFIED AMERICAN NATIONAL/METRIC 2 BLADE GROUPS 28 TOTAL BLADES BLADES INCLUDED: 4, 6, 8, 10, 11, 11-1/2, 12, 13, 16, 20, 28, 32, 40, 56 inch 0.50, 0.75, 1.00, 1.25, 1.50, 1.75, 2.00, 2.50, 3.00, 3.50, 4.00, 4.50, 5.00, 6.00 mm Narrow Designed Blades Permit Use for Internal and External Screw Threads Locking Device at Each End to Secure All Blades for Storage or Position an Individual Blade for Use Correct Pitch is Determined by Matching Blade Teeth with Threads Each Blade Clearly Marked with Proper Thread Size Sets are Available in Wide Range of Sizes and Blade Combinations Blades Protected in Sturdy Steel Case Any Combination of Blades is Available by Special Order Made in USA