3 sensitivity levels - low - medium - high, with an adjustable sensitivity switch on the side. Also functions as a wedge to prevent the door from opening when powered off. No installation required. Requires one 9-volt battery. Portable and easy to add a little peace of mind when traveling or working alone. Extra loud alarm. A 120 decibel alarm sounds when pressure is applied to the door stop. Small size, 5.5 x 1.6 x 1.7 inches Only 95g, lightweight and portable Non-slip bottom Super loud 120dB alarm 3 sensitivity levels: low-medium-high Dual function: security alarm and door stopper Easy to use: Load a battery; turn on the switch; place it under the door, done DIY installation, suitable for wood floor / tile / cement / carpet Ideal for home / apartment / dorm / hotel / travel and so on