Unique patented railing planters can be adjusted to fit railing widths from only 1" wide up to 4" wide. Simply lock the support arm to the desired width, hang and your done. No tools, mounting hardware or drilling required. Sets up in seconds. Ideal for all railings types; wood, metal and vinyl. Hidden lower bracket keeps planters level. Hidden water reservoir keeps plants healthy. Also includes soil tray. Measures 20" wide.