Colours and sizes: these book holders are the same size, 21 x 16.5 x 19.5 cm. Our book stands are available in a variety of colours and combinations for you to choose from, hope you can choose the one you like. (Details as shown in the picture) Stable and durable: the reading shelves are made of high quality metal with a polished and painted surface, which is rust-proof and unbreakable, robust structure that will not easily fall over. With gently cut edges, safe to use without hurting your hands. Ergonomic design: the bookcase has 6 adjustable and switchable angles, with a minimum of 45 and a maximum of 60, which effectively help correct sitting posture, protect the lumbar spine and vision and develop proper reading habits. QUALITY UPGRADE --- Holds books up to 800 pages thick and more stable than plastic and wooden shelves, can be extended in width to hold large books up to 20 inches wide. Turn books quickly and easily with one hand; Foldable design for portable and easy storage. Multifunctional: wide range of applications, does not take up much space, multiple adjustments, suitable for students of different ages and different sizes, can clamp books, documents and magazines of different sizes, and can also be used as a holder for tablets, mobile phones, etc.