Power Supply : AC 110V / 240V 50Hz-60Hz Sensitivity : -44dB +/- 2dB Indicator : LED light on board MS 300C : Priority & ON buttons MS 300D : ON button Frequency Response : 40Hz-16kHz Annular Indicator : Red Ring on capsule Capsule type : Unidirectional electret Mic monitor : Built in loudspeaker System connection : With 8-PIN T-type hand in