JSHD4 AK is a JSHD4 bottom part with a Cannon connector intended for replacement of former non modular Joab JSHD4. It is used with any JSHD4 top part, except JSHD4-1, to form a complete three-position device. It is not compatible with the anti-tamper PCB. 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.