This dual function alarm & door stop keeps intruders out. As soon as someone pushes the door, the 100 dB alarm will warn you that someone is trying to enter. An effective way to frighten away intruders. No installation required. Secures any hinged door & can be used as a non-skid door stop when the power is off. Portable. Goes anywhere you need to feel protected. Requires 2 "AA" batteries (not included). Measures 2 x 5.5 x 1.5 inches.