This is the new and hard to find Star Trek Electronic Motion-Sensitive Door Chime prop replica made by Think Geek in 2015. It can be mounted on either side of a door to alert you when someone crosses the threshold. Choose the door-opening "whoosh" sound effect or the Red Alert alarm. Whether it's a bloodthirsty Klingon bent on revenge or just your boss looking for your TPS report, you'll know the moment they appear with this Star Trek Electronic Motion-Sensitive Door Chime! It measures 6 1/2-inches (17cm) long x 5 1/4-inches (13cm) tall x 1-inch (3cm) wide and requires 3x "AA" batteries, which are NOT included. MINT in manufacturer sealed display box.