Membrane switches, also called membrane keypad, are built from thin polyester film and pressure sensitive adhesive (PSA). Printed Circuit Boards (PCBs) can also be used as the base for a switch. Membrane switches can be tactile or non-tactile, depending on the design. Tactile switches provide a physical "click" when the user pushes it. Non-tactile switches have longer lives, but lack physical feedback to the user. Rubber keypads can be added to the top of the membrane switch as well.