FrSky TFR4 4ch
2.4Ghz Surface/Air Receiver FASST Compatible 
Compatibility:
FASST 2.4G: Air Systems (7CH Mode/Multi Mode) & Surface Systems (C1 Mode)
(3PK 4PK/4PKS etc.)
FrSky TF Modules: TF-8M, TF-14M
Features:
Compatible with FASST 2.4G: Air Systems (7CH Mode/Multi Mode) & Surface
Systems (C1 Mode);
CPPM and RSSI (PWM) output - If CH3 and CH4 are connected by a jumper, CH1
will output CPPM for CH1~CH8, and CH2 will output RSSI (PWM);
Light weight and small size;
Two selectable failsafe setting options.
Specifications:
Number of Channels: 4
Operating Voltage Range: 3.5V~10V
Operating Temperature Range: -10C~80C
Dimension: 34*19*8mm
Weight: 6.2g