1 Box (Each box makes circles that are 12-16 brick pavers round) Introducing the PaverTrax Tree Ring System – A 16 piece unit patented design system that makes landscaping / laying pavers around trees a breeze. Brick (Retaining Wall Block) Requirements: This product is currently ONLY designed to fit around the 3" x 6" x 10" Retaining Wall Blocks as well as the 3" x 5.88" x 10" bricks available at MOST Home Depots. (please check your local Home Depot or Garden Centers FIRST before purchasing) Look Up "3x6x10 Retaining Wall Blocks" at your local garden center website OR on the Home Depot page or follow these links to their Home Depot product page: Works with pavers you already own. PaverTrax is built for standard 3" x 6" x 10" or 3" x 5.88" x 10" retaining wall pavers, like these Home Depot options: Pavestone Rivertown Concrete Retaining Wall Block, Model #80749 Oldcastle Carlton Concrete Retaining Wall Block, Model #16204427 External Diameters (the outer circle of the track): 12 Pavers - 3’ 5” 13 Pavers - 3’ 8” 14 Pavers - 3’ 11” 15 Pavers - 4’ 2” 16 Pavers - 4’ 5” We take pride in the quality of our product and its American-made construction, so you can be confident in your purchase.