ASTM-D2061-Fig18 Zipper Torque Test:

ASTM D2061 covers various strength tests for zippers. Figure 18 within this standard
specifically describes the test device for the slider handle twist test . 
This test method is used to measure the resistance of the slider handle of a zipper to torsional forces.
The device shown in Figure 18 enables the precise measurement of the torque,
which is required to turn the slider handle.