Solid|Drive's RockSolid Sub Has No Holes

Without any perforations in its surface, how does the RockSolid rock speaker emit sound? Using its polyurethane composite surface, which serves as a driver, excited by underlying magnets. Finishes include sandstone, charcoal, red rock, and custom versions. Pricing will range from $500 for a single speaker to $900-1000 for a dual version.