Safety Technology International, Inc. STI-3610 Wireless Motion-Activated Chime with Receiver – When protection is important to you. This wireless chime alerts when someone enters detection zone. This Motion Activated Sensor is great in your garage, inside your home and any area where you feel you need an eye out. Weather resistant sensor helps with moisture and will keep the device running for years. Up to 500 feet operating range (line of sight) between receiver and transmitter. The signal on this device will pass through doors, wall and floors for even greater protection. The selectable detection zone ranges from 20 - 42 feet. There are ten selectable chime options with the push of a button on the transmitter. A CR123 Lithium battery is included. The receiver has a low and high volume adjustment, so you can set it any level. Note: End user must verify the alarm and battery function every six months and replace battery annually or as required. External dimensions - transmitter 2.7”L x 3.325”W x 3.075”D - mounting bracket 3.3”L x 1.575”W x 1.5”D - receiver 5”L x 3.25”W x 1.425”D. STI "We protect the things that protect you."