We use glass reed switches materials with stable quality and long service life. You can take it apart and compare it.

Door and window burglar alarm \ chassis alarm, easy to install, stable and affordable
        Using electromagnetic induction technology, the installation is simple and the price is cheap. In the open state, as long as the doors and windows are opened, the machine will send a 90db alarm sound. Keeping you away from anti-theft doors and windows brings you inconvenience. Enjoy the sunshine and freedom.
Purpose: it is installed in doors and windows, cabinets, computers, drawers and other places where others are not allowed to open the door or window or computer case in the family, company and warehouse; or when an outsider who stays in the hotel opens the door on a business trip, it will send an alarm. Please check it immediately to ensure that your property and safety are damaged.
Use: you only need to tear the laminating film on the back of the security alarm burglar alarm and stick it on both sides of the door or window (leaving a gap of about 0-2cm). When you use it, just turn the switch to the "ON" position and it will be in the standby state. If someone moves or opens the door, computer case or window drawer about 0.5-2cm gap, it immediately sends an alarm to deter thieves and remind you to check until you turn the switch to the "OFF" position or you close doors and windows, computer cases, and drawers.
This product uses 3 tablets of 1.5V AG13/LR44 button battery (already included in the machine). This product consumes less power.