MR-900 series products are characterized by attractive appearance, low power consumption, small quiescent current and wide voltage scopes that have a good protective capability for insects and impurities and shielding of electromagnetic radiation interference capability, quality is reliable for purpose of two-wire system detector and bus-mode alarm detector. Monitoring Room LED light does not flash, but flash when alarming. The controller manufacture also can buy our code base plastic parts and metal parts which code base printing plate can be self-designed by them for comprising bus-mode addressing fire alarm system.