This is 4×4 16 button keypad matrix and The buttons are denoted by numbers and letters: 0,1, 2, 3, 4, 5, 6, 7, 8, 9, *, #, F1, F2, F3 ,F4, which can be used easily for many of your arduino and AVR project.

Device	Keypad
Type	4×4 | 16Key | Hex Tact | Switch