Wrist Straps are the first line of defence against electrostatic charges build up on the human body. They are designed to carry away this charge as soon as it is generated. At the same time the strap must remain electrically safe for the user. Thus, it is important to test every strap regularly.
In order to protect sensitive electronic components the maximum strap resistance should not be more than 10 meg ohms. On the other hand, the path to ground should have atleast 750 kiloohm resistance, as protection to the wearer from dangerous voltages and levels of current flow.
The wrist strap tester checks these parameters under actual operating conditions with the strap on the wrist. It clearly indicates whether or not the resistance of the strap system including the wearer falls within acceptablelimits.