MXR 135 - Smart Gate. Tame your hissing high gain amp or silence your string of stomp boxes with this ingenious pedal.  

Switchable hiss, mid-range or full noise reduction lets every smallest detail of your playing through. This little genius possesses the uncanny ability to sense precisely when and how fast to engage. 

Features precise threshold trigger and amazingly clean circuitry. Hardwire bypass. Powered by 9 volt battery or AC adaptor (RPC921R).