FM Membrane Switch Keypads NKK Switches FM Membrane Switch Keypads are easily integrated into designs and replace multiple mechanical switches, soldered wire, and cable assemblies. These membranes offer non-illuminated options in 4 or 16 keys and illuminated options in 12 or 16 keys. The FM Series Membrane Switch Keypads feature actuating domes which offer crisp, tactile feedback to positively indicate circuit transfer. These membranes also offer adhesive backing for easy mounting.