Seco Larm E-9622-4B25 Photobeam 

These infrared photobeam curtain/barrier sensors are perfect for installation in windows, doorways, skylights, fence tops, any place where space is limited. Suitable for indoor and outdoor perimeter security, the trigger is programmable for simultaneous breaking of any single or 2 adjacent beams. The design features rugged aluminum construction, and an anti-tamper circuit for triggering an alarm if power is cut or the end cap is removed.  No synchronizing wires are required and the LED alignment indicator makes installation easy. L-brackets and mounting hardware are included.

Features

• Rugged aluminum construction
• LED alignment indicator
• No synchronizing wires required
• NO/NC relay output
• Weather-resistant IP54 construction
• Slimline design (7/8" x 1-5/16" cross section)
• Trigger by simultaneously breaking 2 adjacent beams or any single beam (programmable)
• For windows, doorways, etc., where space is limited
• L-brackets and mounting hardware included
• Multi-Frequency: Reduces interference and eliminates crosstalk when multiple units are used in close proximity to one another

Curtain Sensor. Length: 22½", with four photoelectric beams. Range: Up to 25ft outdoor and 50ft indoor. NO/NC relay output, anti-tamper circuit, and LED alignment indicator. Black enclosure.