The 4 X 4 Matrix Keypad (RM0947) is a very simple one which have 16 tactile keys connected to the male headers across the resisters on the same board. It is very small and easy to carry. Its simplicity is just to give the power to the keypad and connect the headers to the microcontroller's input port with 8 pin female connecting wire. When one tactile key is pressed its corresponding pin with Rows and column intersection gets high logic.