What is a layered antistatic mat?
These mats have more than one layer of different materials sandwiched together. Usually one of the internal layers is conductive, a top may be dissipative and a bottom layer could be insulating. By bolting through this mat to a ground point an electrical contact is made with the conductive layer, there is some discussion regarding the disrupting effect that this alternate parallel ground path may have on persons safety which are already grounded through their wrist or footwear straps to ground.