Proper's four-disc, budget-priced but hardly shoddy box Classic Rockabilly can't quite be called a proper introduction to rockabilly -- there are too many classic singles missing for that. What it can be called is a great second rockabilly box to get (probably after Rhino's crash-course introduction Rockin' Bones, a master's course in cat clothes and rockin' rhythms). Which isn't to say all 120 of these songs are obscure. Many of the best and biggest Sun sides from Elvis, Carl Perkins, and Roy Orbison are here, along with Gene Vincent's "Be-Bop-A-Lula" -- songs that are pretty close to very first rockabilly anybody ever hears -- and there is even a decent share of good second-tier rockabilly that isn't exactly uncommon (including cuts from that aforementioned Rhino box). But there is also much more high-quality music that warrants further exploration by rockabilly fans of all stripes. Plus, there is a certain joy to the sequencing -- where all the songs about rockin' are followed by songs with "cat" in the titles, then a bunch of tunes about Cadillacs and bops and boogies, then finally nearly a whole disc of songs with "baby" in the titles -- which helps make this already fun set just a bit more of a gas.