JSHD4 AL is a JSHD4 bottom part with a holder for an Eva actuator, a cable gland and 10 screw connections. It is used with any JSHD4 top part to form a complete three-position device. A JSM54 is ordered separately to be used with the Adam sensor. Three-position devices are used to allow a limited movement of the machine when the operator is in the dangerous area, for example during troubleshooting, test running and programming.