This is the Futaba SBS/02A height / variometer sensor it is a very popular choice amongst pilots. This Futaba Atmospheric Telemetry Sensor indicates the altitude of aircraft from atmospheric pressure

Features
* Range: Altitude about 700 - 5,500 m
* Vario Meter -150m/s - +150m/s

Specification
* Length: 175mm
* Weight: 2.6g
* Voltage: DC 3.7 - 7.4V

Includes
* Futaba SBS-02A Atmospheric Sensor
* Instruction Sheet

Compatability
Futaba 18MC-WC, 18MZ, 18SZ, 14SG, 10J and 6K telemetry systems*

Please Note
This item May only be used with telemetry enabled receivers that have
S.BUS 2 ports. Refer to the manual for the system(s) listed above
to ensure proper connection..