4x1 keypad has 4 keys in it. These switches can be used as a general purpose keys for interfacing with microcontrollers. The i-labz 4x1 keypad has 5 pin male connectors in the board. The 5th pin on the board is commonly connected to all the four switches and it can be used as ground pin while connecting it to microcontroller or other development boards. You can use 4 bit female to female connector for connecting with development boards.