From the manufacturer: Deck Rail Planter Collection: : Maximize your gardening space with the Bloem Deck Rail Planter collection. It's great for any home, including apartments and condos that may have limited gardening space. This planter was designed to maximize inside growing space and features a tiered bottom design allowing dirt and roots to grow strong and deep. Compression design fits rail size 3.75" or 5.5" wide. Rail planter also works on widths slightly smaller (3" up to 3.75" OR 4.75" up to 5.5"). For smaller rail sizes we recommend securing with screws or zip ties (not included) under railing for added stability. Available colors: Terra Cotta (pictured), Chocolate, Charcoal Available sizes: 12" (Round), 24" (Oval) Made from durable resin plastic to prevent fading and cracking Great for growing herbs, strawberries, or showcasing favorite florals Use on patios, mailbox posts, balconies, fences, or deck railings Snap-on design makes it easy and ready to use Optional drillable drainage holes Proudly made in the USA Product Description: Pack of 2 Compression fit design ensures a secure fit on either 4" or 6" wide rail Use on patio, mailbox post, balcony, fence or deck railing Optional knock out drainage holes Width 12" (x) depth 12" (x) height 9" Matte finish is perfect for resisting scratches, dirt, and fingerprints