The structure of anti-static heel straps
The anti-static heel straps release static electricity from a person's body to the earth by connecting the person to a grounded ground. Conductive tapes placed inside the wearer's shoes or socks make electrical contact with the skin through sweat. The conductive tape is connected to a resistor that limits the flow of electricity in the event of accidental electrical contact. The other end of the resistor is connected to the conductive shoe sole, through which it contacts a grounded anti-static floor mat or static floor system.
Foot grounders must be worn on both feet to maintain the integrity of the body's connection to the ground, and anti-static hamstring straps on each foot ensure contact with the ground through the anti-static floor, even if one foot is lifted off the floor It can also ensure that the grounding of personnel is OK. This will more reliably remove static charges generated by human movement and protect ESDS more reliably.
IEC 61340-5-1 recommends a resistance to ground (Rg) of at least 1 megohm to limit unintended current flow to 0.00025 amps.
"For standing operations, personnel can be grounded through a wrist strap system or a shoe-to-ground system. When using a shoe-to-ground system, personnel should wear anti-static shoes on both feet and meet the following two conditions:
The total resistance of the system (from person, shoes and floor to ground) should be less than 1.0 × 109Ω;
The maximum body voltage produced should be less than 100V. "