A: one-way (5V power supply) Features of one-way type: 1 channel servo signal input, control one-way electronic switch. Max control 20A current. Only supports 5V voltage receiver, otherwise it may cause module damage. If the receiver and servo use a high-voltage system, a voltage reduction module should be added to the module before it can be used. PWM frequency: 50HZ. PWM cycle: 20MS High level: Greater than 1700US on, Less than 1300US off Size: 41x16x14mm Cable length: about 30cm Weight: about 13g Used for RC model airplane, car, boat Description of one-way type: 1. Connect: Plug the signal input cable into an idle receiver channel that corresponds to a switch on the remote controller. The power indicator will be illuminated when connected to the receiver. The work indicator lights up when the switch channel is open and vice versa. 2. Working mode: The LED light indicates the power indicator and relay's operating status. 3. Trigger: Turn on the switch (OFF→ON) on the remote control, the green LED light will turn on, and the relay will start working. / B: two-way (5V power supply) Features of two-way type: 1 channel servo signal input, control two-way electronic switch. Only supports 5V voltage receiver, otherwise it may cause module damage. If the receiver and servo use a high-voltage system, a voltage reduction module should be added to the module before it can be used. PWM frequency: 50HZ. PWM cycle: 20MS High level: Greater than 1700US channel 1 is on, Less than 1300US channel 2 is on, 1300-1700US the channels are all closed Size: 41x25x14mm. Cable length: about 30cm. Weight: about 20g. Used for RC model airplane, car, boat. Description of two-way type: 1. Connect: Plug the signal input cable into an idle receiver channel that corresponds to a switch on the remote controller. The power indicator will be illuminated when connected to the receiver. The work indicator lights up when the switch channel is open and vice versa. 2. Working mode: The POWER LED indicat