The VGA-AB2 is an A/B switch box that allows you to share a single VGA monitor or TV with two different computers or digital video recorders (DVRs).  This device is very convenient in situations where you have a computer located close to where your surveillance DVR will be located and you do not want to add an additional monitor or you do not have room to do so.  Simply plug both devices into the AB splitter and select which one you want to appear on the shared monitor.  This switch box is limited to a max resolution of 1024 x 768.