The FrSky Variometer sensor calculates the altitude from atmospheric pressure. Atmospheric pressure will get lower as you go up in altitude, using this the sensor will estimate the altitude. An exact display cannot be performed if atmospheric pressure changes in weather. The Variometer sensor also can output the Altitude Rate via DA port. Altitude Rate formula: (Output DA Voltage -1.65)/1.65=Altitude Rate speed/10.24.

Capable of connecting directly to the telemetry receivers without the sensor hub.
Backward compatibility with existing sensor hub and sensors, also compatible with new generation Smart Port enabled sensors.
Smart Port enabled, realizing two-way full duplex transmission.

Type: Variometer sensor
Measures: -700 ~ 10000 m with 0.1 m (high precision version) resolution
Operational Voltage: 4~10 VDC
Operational Current: 30 mA
Dimensions: 31.1×18.3x6 mm (LxWxH)
Weight: 3.1 g
Units: Metric or British units