FrSky receiver TFR4 is support 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).

FrSky receiver TFR4 has two selectable failsafe setting options.

FrSky receiver TFR4 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).
Lighter weight and physically smaller.

FrSky receiver TFR4 Specifications:

Number of Channels: 4
Dimension: 34 x 19 x 8mm
Weight: 6.2g
Operating VoltageRange: 3.5V~10V
Operating TemperatureRange: -10°C~80°C

FrSky receiver TFR4 Compatibility:

FASST 2.4G:
Air Systems (7CH Mode/Multi Mode): 6EX, 7C, TM-7, TM-8, T8FG, T10C, TM-10, T10CG, T12Z, T12FG, TM-14, T14MZ, etc.
Surface Systems (C1 Mode): 3PK 4PK/4PKS etc.

What's in the Box:

1 x TFR4
2x Short tool
1 x Manual

From: https://www.horusrc.com/en/frsky-tfr4-2-4g-4ch-surface-air-system-fasst-compatible-receiver-cppm-rssi-output.html