VSS-E-DVG-BL-FHold Economical Vacuum Safety System with a Digital Vacuum Gage and an Alarm Buzzer and Light with 24VDC Feed Hold Signal. The unit comes complete with a digitally adjustable low vacuum safety sensor that can be set via a digital LCD display. In addition, the digital sensor has an hysteresis setting to avoid "chattering" (bouncing back and forward between the low vacuum setting). The digital display is fastened to a NEMA 12/13 mountable enclosure and a 1/4" hose barb with approximately twenty (20) feet of vacuum hose to tie into the vacuum line (near the vacuum chuck). The unit operates on 110V, single phase power and has one (1) selector switch which engages the vacuum safety system operations--feed hold and an alarm buzzer and rotating red light to indicate a loss in vacuum pressure. The unit comes with a built-in by-pass function of the alarm and light when the vacuum workholding system is not in use on your machine during your workpiece set-up (below 2"Hg). The unit has a three (3) wire connection that interfaces to the machine tool Feed Hold. Recommended for a single vacuum line only.