All the information you need to know about these, including partial (sometimes complete) tracklists and some really cool photos, can be found on this website. Here are some brief descriptions of mine of each installation.
Vol. 1 is mostly a Stones Throw sampler, featuring remixes of tracks by Madvillain, Quasimoto, Oh No, MED, Wildchild, and others, but also including material by Method Man, Common, and Bobby Hutcherson.
Vol. 4 focuses on hip hop, and includes a set of Nas vs. Jay Z remixes.