Based on this product's specifications, here are some alternatives and similar models
Door Contact Sensor No name KN-CA56D – wired magnetic reed switch KN-CA56D
Summary description:
Wired door contact sensor No name KN-CA56D is a magnetic reed switch designed to detect opening and closing of doors or gates. The KN-CA56D consists of a switch and magnet for installation on a door frame and door leaf; it provides a simple normally closed/normally open contact for alarm panels, access control or automation systems. Suitable for indoor/outdoor mounting where a wired door/window status input is required.