Opening sensor for windows or doors for GSM alarm

A wireless reed sensor is installed on a window or door and is triggered when the contacts open. Works in conjunction with GSM security alarm.   Characteristics: - The sensor reacts to the opening of a window or door; - Used together with GSM security alarm system; - Wireless sensor operates at a distance of up to 100 m; - Wireless frequency: 433 Mhz; - The two sensor contacts must be installed with a distance of less than 15 mm between them; - Operating temperature: -20 ~ 70 C; - Power: from 12V battery; - Attached to the surface using double-sided adhesive tape; - White color; - Size: 71 x 36 x 15 mm.