What's in the box:

DC12V Infrared Photocell Beam Sensor Automatic Gate Door Garage Shutter Barrier Detector for Door Window Burglar Alarm System Sliding Gate Opener Accessory 24V 1 Pair(Transmitter and Receiver) (Standard)

Features:
Wide Application -- Works for all gate openers. Can be widely used for access control system, parking lot, defence wall, door and window, balcony, garage, passage and other places. Great to be installed for security system in school, office building, hosipital, home yard, etc.
Stable Signal Transmission -- High-power infrared transmitter & receiver. The transmitter creates a reliable and invisible infrared beam up to 65in (20m). When interrupt the infrared beam, the relay will output switch signal.
Waterproof & UV Proof -- Fully-sealed waterproof and dustproof egg shaped cover, sunlight-filtering case, enables it to work in harsh environment. Easy installation.
Reliable to Use -- Features advanced security technology that ensures multiple protection & safety. Infrared Photocell beam will make the gate stop or reverse automatically in case of obstruction happening to protect your safety and property.
Easy to Install -- Install each pair at the opposite positions.Then there is a infrared area between these two detector parts. When someone passes the infrared region, the detector will send alarm signal to the security alarm host (which not included here).

Specification:
Color: Black
Material: PC (Water Proof, UV proof)
Detect Area: Outdoor: 20m; Indoor: 30m
Detect Speed: 30ms
Infare-Red Frequency: 1.92Khz
Wave Length: 940nm
Working Voltage: DC 12-24V
Input Curren: RX 15mA - TX 30mA
Relay Output: A1 36W
Item Size: 76*49.2*21.6mm/3.0*1.9*0.9in

Packing List:
1 * Pairt of Infrared Sensor( Transmitter and Receiver)