Motorola PMMN4050A Large Remote Speaker Microphone with Noise-Cancelling Feature (Black) large remote speaker microphone (RSM) is easy to operate even while wearing gloves and features IMPRES audio which optimizes your audio when operating in noisy environments. The noise-cancelling feature reduces distracting background noises. Audio jack available to attach earpieces for discreet communications. Compatible: APX 2000, APX 4000, DP3401, DP3600, DP3601, DP4400/DP4401, DP4600/DP4601, DP4800/DP4801, MTP830 S, MTP850 S, XPR 6100, XPR 6350, XPR 6380, XPR 6500, XPR 6550, XPR 6580, XPR 7550 IS This RSM conveniently clips to your shirt pocket or lapel and enables easy communication without having to remove the radio from your belt.