Screw pitch: Whitworth
Blades: 28
Threads per inch: 4, 4.5, 5, 6, 7, 8, 9, 10, 11, 12, 14, 16, 18, 19, 20, 22, 24, 25, 26, 28, 30, 32, 36, 40, 48, 60

- Designed to check both internal and external thread forms
- Accurately milled steel blades
- Marked with nominal size on each blade
- All blades fixed in a steel sleeve
- Screw cutting gauge included 55 degrees