Based on this product's specifications, here are some alternatives and similar models
Door contact sensor No name KN-CA55L — wired magnetic reed switch, surface-mount
Summary description:
KN-CA55L is a wired door contact sensor (magnetic reed switch) by No name, model KN-CA55L. Designed for surface mounting on doors or windows, it provides a simple open/closed signal for alarm panels and access control systems. The sensor pair includes a contact unit and a magnet; it is suitable for perimeter intrusion detection and status monitoring in residential and commercial installations.