MXR's M87 Bass compressor has been around for a little while now, and the new M76 Studio Compressor is more of the same, but with a new look and name, aimed to give it more universal appeal.
This is based on the sort of classic compressors you would find in studios, with a choice of compression ratios as found on Urei's rackmounted 1176, plus attack and release knobs to give you control over shaping the envelope of the sound.
You also get a very useful green/orange/red LED meter showing you the amount of gain reduction that's going on.
The M76 is a naturally transparent-sounding compressor rather than one providing an obvious sonic signature. In this respect, it's a very different beast from MXR's Dynacomp, which is still a favourite with guitarists for its own flavour of snap and squash.
With no top-end dulling, this is a pedal that will unobtrusively keep your dynamics in check, whether just thickening the sound, keeping levels consistent or making it chime. Class.