Intercom Central Do-It Yourself DIY-ICW138 Basic Hot Wired monitor & Intercom Installation is REQUIRED. See Knowledge Base... 2nd picture in the picture gallery for detail *** NEVER buy More than One set *** Long battery operation, low power consumption. See Knowledge Base...2nd picture in Picture Gallery Battery operated (batteries NOT included) +++ Optional U/L approved AC adapter INCLUDED. Indoor use only *** one year warranty