The JSHD4-2 is a top part of a three-position device JSHD4. It has LEDs, a front button and a top button. It must be used with one of the following bottom parts: AB, AD, AH, AJ, AK, AL. Anti-tamper can be chosen as option with all except bottom part AK. 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.