Check the listing for details. Optogate in-line audio mute microphone switch automatic optical proximity sensor. Condition: New. Listed at 300.00 USD. OptogateOnline com Optogatemicswitch(.) com For best price German manufactured professional audio equipment. PureSound & Light, LLC OptogateonlineUSA and South American Pro audio equipment Distributor . Improve audio/ sound clarity (People started to ask me if I got better equipment lol ) Eliminate open mic issuesImprove vocal microphone technique Lower the stage volume and save your ears (I stopped getting ringing in my ears when I started using these and I could actually communicate better to other musicians on stage)Increase headroom and capacity of amps and speakers (Because there isn’t any feedback getting through from ambient noise your amps and speakers with gain headroom that otherwise went to the open mics) Optogates are in-line (through xlr )automatic microphone switches that enable mute (-48db) or audio ducking (-16db) through an infrared optical proximity sensor. It can sense when vocalist is in front of mic and will automatically turn on.When vocalist is absent from the infrared proximity sensors range the microphone is muted or ducked. Which do you want: the automatic mute switch Or the automatic audio ducking switch