2M on the box means the cable length of the sensor, not detection range. 

 Manual not updated and 4m on the manual is not correct.

 Retro-reflective sensor for gate opener, boom barrier:

 For the power supply, there are 110V/220V version and 12V/24VDC version:

When installing it, make sure no sunshine interference: 

 -- Light resource: Infrared LED 

-- Strong anti-shock and anti-vibration. 

-- Non-contact object detect: Avoid the photoelectric sensor to contact the object directly, protect the inducing component from damage and extend the operation life of the sensor. 

-- Detect any objects with different materials: Detect objects by the light quantities reflected and received, detect objects such as glass, metal, plastic, wood, fluid...etc. 

--   Fast response: Max. 3ms 

-- Identify object colors: According to the colors' reflectivity and absorptive, the sensors detect the light that the object reflected and identify the colors. 

-- High precision: Precise electron circuit can detect tiny objects with accurate position.