Based on this product's specifications, here are some alternatives and similar models
Cylindrical Reed Switch KONTAKTRON KN-CA36-B, model KN-CA36-B by No name
Summary description:
Cylindrical reed switch KONTAKTRON KN-CA36-B (No name) — magnetic contact sensor in a cylindrical housing for detecting proximity or door/window positions. Designed as a normally open/closed magnetic contact (model KN-CA36-B), used in security systems, alarm panels, access control or position sensing. Compact cylindrical form factor allows mounting in frames or surfaces where a small magnetic contact is required.