The by-m1dm from boya is a double lavalier microphone, which is suitable for smartphones and (dslr) cameras. thanks to the cable length of four meters, you have enough freedom of movement. the special feature of the by-m1dm is that it is suitable for both smartphones and cameras. with a special button you can switch between these two modes. when you use the by-m1dm with a camera, the lr44 battery does its job; this gives the microphones their power. a 3.5mm to 6.3mm adapter is included to connect the by-m1dm to more professional cameras. Usage by-m1dm With the by-m1dm you can interview two people at the same time and record the sound. the sound of both microphones is recorded together on both tracks (mono). thanks to the universal deployment (cameras, computers and smartphones) and inexpensive costs, the by-m1dm offers a solution for the starting and advanced filmmaker. a tie pin and windshield are included for both microphones. you will also receive a handy storage bag. Technical specifications by-hlm1 - duo lavalier microphone - frequency range: 65hz ~ 18khz - output impedance: 1000 ohm - sensitivity: -30db +/- 3db / 0db = 1v / pa, 1khz - signal / noise ratio: 74db or more - weight: 68 grams