The Alpha-Series Motion Alert Kit contains a PIR (passive infrared) motion sensor & a chime receiver unit. It’s very easy to install as all units are battery-powered and completely wireless! Use the included installation accessories to set up in minutes. Mount the PIR motion sensor wherever you need to know about movements and be alerted audibly and/or visually from the chime receiver unit that has 3 selectable volume levels. This kit is perfect for creating cost-effective safety in and around your home with modern units that have reliability, accuracy and ease of use at their core.