... service quality.Programble and controllable computer chip. Different colors of LED to show "DND","clean room" and "bell", ... doorbell, four-in-one doorbell, big room number doorbell, disc big room number doorbellApplicable to hotels, guesthouses, apartments, conference ... too.Plastic: Hotel doorbell (touch panel)/Hotel doorbell system/ hotel room control panel/electrical hotel bell/door chime/door bell ...