This Adjustable Planter fits to any rail from 1-4", giving you a new "green space" for flowers, vegetable, herbs, whatever you'd like! There are no tools, hardware or anything required. Its arms extend up to 4" and it has a lower arm that braces it to keep it level. It's 24" long, 7 1/2" wide and 7 1/2" tall. A "grate" at the bottom creates a reservoir, holding and gradually releasing any excess water. Made of tough, weatherproof plastic in a white color.