Steel. [Your Rack, Your Way] With a customizable design, you can extend it infinitely with similar shelves—at least until it reaches the limits of your walls; also, the shelf height is adjustable so your plants or decorations can all have a home here, big or small. [High-Quality, Our Way] The strong metal frame used in this storage rack means extra strength and durability, ensuring a static load up to 22 lb per shelf. From your towels to your numbers of cleaning supplies, they'll sing songs of praise to this silent hero. [It's Only for the Bathroom?] Nope. Create a secret garden on the balcony to unwind from worldly life, use it as a shelving unit in your living room to hold an art collection, or blend it in alongside your kitchen counters—this all-rounder can always be in full play. [Assembly Finished!] With SONGMICS, no unpleasant surprises! Easy-to-understand, illustrated instructions, assembly kit, and numbered parts make it easy to assemble this storage shelving unit. You might surprise yourself! [Keep Stability in Mind] We've packed a stability trio into this 11.8″D x 15″W x 28.4″H storage shelf—the strong steel frame, anti-tip kit, and adjustable feet ensure the storage cabinet is stable enough to hold a vase of fresh flowers safely.