... improve service quality.Programble and controllable computer chip. Different colors of LED to show "DND","clean room" and "bell", very personalized ... one doorbell, four-in-one doorbell, big room number doorbell, disc big room number doorbellApplicable to hotels, guesthouses, apartments, conference ... in the dark. 3. High quality PC material , fire proof 4. Touch panel is scratch resistant glass, more ...