GLASS BREAKAGE ALARM is the perfect low cost security solution for homes and businesses. This alarm's powerful vibration sensor is triggered when glass is hit, knocked or broke by anyone. Once triggered, it sets o a loud 100dB siren alerting anyone nearby of a break in as well as scaring o any intruders. The 100dB siren will sound o for approximately 30 seconds and then shut o and reset.Easy installation: All you need to use to install is the included peel o adhesive and then simply mount onto the window and switch on the alarm mode. Two units included to ensure double the protection!Each unit is powered by 3pc AG13/LR44 battery (included for both)• 2 units included• ON/OFF switch• Fits any doors and windows• Easily mounted by double-side adhesive tape• Measures: 2 ½” x ¾”ST-DG • $9.00ST-GLASS • $15.0042