The Ubiquiti mFi mFi-DS Door Sensor is a magnetic switch sensor. It is designed to detect open entry points, such as doors, windows, or other physical enclosures.  
Ubiquiti mFi-MSW mSensor Specifications
Dimensions

    50 x 9.5 x 7.7 mm (Magnet)
    50 x 9.5 x 7.7 mm (Switch)

Contact Form

    Form A (SPST)

Maximum Rating

    1.0A @ 28VDC

Initial Contact Resistance

    0.3 Ω Maximum

Operating Range

    20 mm (Typical)

Wiring

    Screw Terminal

Mounting

    Adhesive or Screws (Included)

Operating Temperature

    -10 to 60° C

Operating Humidity

    ≤80% Condensing