Because the die has a split it can be adjusted slightly to provide a thread slightly smaller or larger than the norm.
Metric Coarse Adjustable Dies.
Application: For production of external threads less than three times diameter in length.
Also available in MF, UNC, G(BSPF) thread forms.
Tolerance: 6g Adjustable.
Chamfer Lead: Two Threads.
Surface treatment: Bright.
Material: HSS - High Speed Steel.
Thread: 8mm x 1.25.
Diameter: 1 5/16 in.