The Polk Audio PB 55 Pre-Construction Bracket works with RC55i speakers. It attaches to your studs or joists before drywall is hung. It designates the exact location and exact cut space, where your loudspeaker will be installed. It gives your electrician a wiring target and give your drywaller a hole template.
The pre-construction bracket adds that extra pinch of energy-harnessing, super-efficient rigidity that a Built-In Speaker needs, one more step toward keeping your built-in loudspeakers vibration-free, with added efficiency and less audio "print through."
It is the inexpensive alternative to custom performance enclosures and gives you more flexibility for speaker placement.