This is a set of 315Mhz Wireless RF Transmitter and Receiver. The transmitter includes an inbuilt battery, 4 buttons and comes in a small package and can also be used as a keychain. The receiver has 4 output pins. The four output pins on the receiver change from 0V to 5V when the corresponding button on the transmitter is pressed.
The receiver works on 5V and its output can be used to control LEDs, Buzzers, Relay Boards(to switch high power loads - motors, 240V Applicances, etc) directly without the need for any additional circuits. The receiver outputs can also be connected to an Arduino, Raspberry Pi or any other micrcontroller to read the status of the buttons on the transmitters. The receiver also has an additional output pin which goes high when any one of the four buttons on the transmitter are pressed. This can be connected to the interrupt of the micrcontroller to read the button status faster.
This remote is great for building wireless DIY Projects, home automation projects, etc.