The YK110 with 1 key, it is suitable for emergency help or remote control  wireless switch. Press it to send out encoding 433 MHz wireless signal to the receiver or wireless switch. The wireless switch includes the wireless receiver and decoding it, and then transmits signal to the MCU to make the relay close or open. It is useful in lots of local remote control applications, e.g.: gate, garage, door, or light, lift, and other appliances or devices.