Designed to check both internal and external thread forms.
Marked with nominal size on each blade.
All blades fixed in a steel sleeve
No. of blades - 30.
Size - 60 degrees.
Threads per mm - 0.25,0.3,0.35,0.4,0.45,0.5,0.55,0.6, 0.65,0.7,0.75,0.8,0.85,0.9,1.0,1.1, 1.2,1.25,1.3,1.4,1.5,1.6,1.7,1.75, 1.8,1.9,2.0,2.5,3.0
Note: SI (System International) metric blades should not be used to check ISO (International Standards Organisation) metric threads due to interference of the thread forms; but ISO metric blades can be used to check SI metric threads.