OEM Systems VPD-8 Rough-In Kit/Vapor Dome/Back Box Combination for 8" Round Speakers: * Mounting straps span 24" members * Dome/mounting flange slides along straps * Substantial friction holds ring fast * Inexpensive * Versatile * Wire inlet * Shields speaker for insulation * Metal straps span 24" on centers * For 8" round speakers * Mouth opening: 8-5/8" round