This planter is great for home or apartment use and helps you make the most of your porch or patio living space. Grow a mini garden in an elevated space. 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 under railing for added stability (screws not included). Planter was designed to maximize inside growing space and features a tiered bottom design allowing dirt and roots to grow strong and deep. The planter features a smooth texture with matte finish. Made of durable resin, this planter by Bloem is 100-percent UV stable to prevent fading and cracking and ensures long-lasting use. BPA free. Includes optional punch out holes for drainage. Use on patio, mailbox post, balcony, fence or deck railing.