Building on the popularity of Legend, the best-selling reggae record of all time, the Marley estate brings us “a collection of 20 vital singles,” including several that didn’t appear on that set: the Lee Perry-produced “Soul Rebel,” an early version of “Lively Up Yourself,” the heartfelt favorite “Trenchtown Rock,” the original Tuff Gong mix of “Concrete Jungle,” “Roots, Rock, Reggae” (Marley’s one single to hit Billboard’s Pop chart), and “Sun Is Shining,” which has become popular again via remixes and adaptations. All of these have appeared many times elsewhere (for good reason!), but a few new tracks will tempt the serious Marley collector. “Slogans” is a “fleshing out” of an acoustic recording Marley made in a Miami hotel room in 1979. Even if it didn’t feature an Eric Clapton guitar solo, it would be a notable addition to Marley’s catalog, achingly earnest and very well produced. Ashley Beedle remixes “Get Up, Stand Up” for everyone who can’t get enough of that Jamrock rhythm, but Black Eyed Pea will.i.am’s unnecessary reworking of the title track mars (slightly) a wonderful Marley mix.