The FrSky TFR4-B is a 4-channel receiver with an operating voltage of 3.5V to 10V and an operating temperature of -10℃ to 60℃. - Brand: FrSky - Model Name: TFR4-B - Number of Channels: 4 channels - Operating Voltage: 3.5V-10V - Operating Temperature: -10℃ to 60℃ - Dimensions: 42*19*18mm It seems to have been compatible with Futaba 4PK transmitters, etc. at the time, but I don't know the details. Although it is new, there may be age-related deterioration, so please understand this. The product description is provided by AI, so please use it as a reference. Type...Radio Control