Based on this product's specifications, here are some alternatives and similar models
Magnetic Contact Sensor SATEL B-21-BR — cylindrical door/window reed switch, brown finish
Summary description:
Cylindrical magnetic contact sensor SATEL B-21-BR designed for monitoring status of doors and windows. The reed-type contact provides a magnetic switch in a compact cylindrical housing with brown finish. Suitable for use in alarm and access-control systems to detect opening/closing of panels and trigger security circuits or automation inputs.