... , airport and shopping center, etc. APM212 of noise-decrease to two-way monitor adaptor, as the ... most advanced noise-decreasing product in the world, it can ... input,via it mix sound output;4.noise filtering.APM212 same as APM210,but APM212 ... APM210,mainly for noise reduction,effect of noise filtering is the top and wonderful. APM212 noise cancelation microphone adapter