Button Pad Sealed Membrane 4X4 With Sticker

This module is a 4x4 keypad membrane matrix that is connected using 8 digital pins. It has a size of 70mm x 77mm x .8mm pad size, with its cable length of 85mm. It also has 8 female Dupont headers that can be connected to your Arduino through the digital pin. 

The input power is up to 35V with 100mA current.

It works by having the 4 pins connected to the column pins and the other 4 to the rows pins.

It detects a pressed button by checking which row pin and column pin states changed.

It is easier to add this to your project than having a series of tactile switches. It only needs 8 pins of your Arduino digital pin to control 16 buttons.