MXR M76 Studio Compressor

Studio-style Control Over Your Guitar's Dynamics
Whether you want more sustain, a softer attack, or just want to even out your guitar tone, you'll have the dynamics control you need in the MXR Studio Compressor pedal for electric guitar. With controls for Attack, Release, Ratio, Input, and Output, plus an LED gain reduction meter, the Studio Compressor pedal gives you the same control you'd expect from, well, a studio compressor. 

MXR Studio Compressor Pedal Features at a Glance:Compressor pedal for electric guitar
Precise control over your dynamics with controls for Attack, Release, Ratio, Input, and Output
10-segment LED meter displays gain reduction amount
True-bypass switching completely removes the effect from your signal path
CHT (Constant Headroom Technology) ensures clean, clear audio