To en iso 13856-1 when used with safety controller easy to install two-wire fail-safe connection is achieved when used with bircher reglomat safety controller & resistor (resistor supplied complimentary) can also be wired as a four-wire system each mat supplied with two 12 foot 2 x 20 awg wire leads inside 5 awg pvc jacket, exiting the middle of the longer side of the mat mat is black with non-skid diamond surface pattern Safety Switch Mat 24" x 42" Black may also be used as a signal mat for activation of a device or counter through presence detection.