They are open air. I added a 24" x 24" piece of .25" plywood to the tops of the tiles. This should help keep them from sagging and keeps the bracket from digging into the tile.
I haven't ran Audyssey again, I just manually set them to 80hz. Once the rears come in and are installed, I'll set it up properly.
Equipment - Silverticket 100" - Epson 5040UB - Denon X4300H - Pioneer BDP-150 - HTPC, Xbox One X, Nvidia Shield 4K - Sennheiser RS170 Headphones - APC C25B Power Filter
Speakers 5.2.4 - SVS Prime Center, Bookshelves, Satellites, 2x PB-2000, 4x Micca R-8C (Atmos)
HTPC - Intel Core i3-3220, 8GB DDR3 1600, 1050ti 4GB, 12TB of HDD's, LG Bluray