Pre-Installation Mud Ring Adapter Bracket for VXC Series Ceiling Speakers. Attach to existing tile ring to allow attachment to ceiling joists for drywall installation. Packaged in sets of 2.   
Yamaha Speaker Pro Mud Ring Adapter for 70V/8-ohm VXC Speakers (Pack of 2)
Pre-Installation Mud Ring Adapter Bracket for Yamaha Pro 70V/8-ohm In-Ceiling Speakers (VXC Series) . Attach to existing tile ring to allow attachment to ceiling joists for drywall installation. Packaged in sets of 2.