Best Comp I've tested and permanent on my board. It is one of those you won't hear until you switch it off. Very versatile thanks to the well chosen control options, from a soft knee squish to hard knee limiting if you so desire. The input gain sets how much of your signal is affected... actually the review by ovnilab is fairly accurate, and it's a great site to browse through when looking for a comp:
Http://www.ovnilab.com/reviews/mxrbass.shtml