BackBoxx™ Popp™The deep BackBoxx Popp, with its soft, flexible back wall, is our deeper speaker surround for all in ceiling speakers, providing up to, and over 9 1 2" in depth, when needed. The convex back wall eliminates the need for acoustic dampening because back pressure sound waves are dispersed. Patented design protects ceiling speakers from moisture and dirt, keeps loose insulation out of eyes while installing speakers, maintains vapor barrier integrity.