The front and back are encased by a fine metal mesh, the kind you'd see on a $1,500 surround sound system. It's not exactly rugged, which is why Bose offers a variety of covers ($25) to protect the speaker from the elements.
The sound coming from behind that mesh certainly matches how good this speaker looks on the outside.
The Soundlink Mini was a champ, playing everything from George Gershwin's full-bodied Rhapsody in Blue to Led Zeppelin's sweet, melodic Stairway to Heaven. Midtones were warm yet crisp, low registers had great depth, and the percussions punched through.
James Blake's Limit to Your Love, which has the deepest womping bass of any song I know, was the only challenger. The Soundlink Mini struggles only slightly with the lowest frequencies. The speaker works so hard to accommodate these bass sounds that it vibrates.
This is disappointing to any diehard dubstep or electronic music fan, but the Soundlink Mini is fantastic at producing the sounds of rock, classical, R&B, hip-hop, blues, pop, and just about every other genre.