Optional C-ring and Tile Rail For VXC2F speaker Installation. The other VXC series F models come with O-ring + Tile Rail kits.  
Yamaha Pro Tile Bridge for Low Profile 70V/8-ohm VXC2 Speakers
Optional C-ring and Tile Rail for the Yamaha Low Profile 70V/8-ohm In-Ceiling Speaker (VXC2F) Installation. The other VXC series F models come with O-ring + Tile Rail kits.