Functionality: Chamberlain 771REV Photocells detect obstacles during the closing procedure, for increase safety and security Compatibility: Compatible with Chamberlain automation systems, including garage doors, swinging doors and sliding doors Special Features: IP44 Protection means that Chamberlain photocells are splash-proof, and protected against solid objects that are bigger than 1mm in size. The current draw is 20mA maximum What's in the Box: Each product contains two Chamberlain 771REV Photocells Chamberlain is one of the world's leading manufacturers for Garage door openers and gate openers, Manufacturer: Chamberlain