This solid surface-mounting unit is finished with 7 mm-thick aluminium. Its surface-mounting height is just 20 mm. The external unit is equipped with an integrated colour camera, a 5 mm-thick, vandal proof name plate in Plexiglas and infrared LEDs for better night-time visibility. The metal-plated push-button contacts are maintenance-free and durable. This surface-mounting unit is very well-suited for large residential complexes. This external unit has 4 bells in two rows.