Carrying cases and equipment cases protect contents from impact, shock, vibration, rain, sunlight, and dust. Exterior case materials range from paper, fabric, and fiberglass to aluminum, steel, and stainless steel. Cases made from durable, molded plastic and thermoplastic materials are also available. Foam-lined, custom, and specialty interiors provide additional protection, especially for sensitive instrumentation and laboratory equipment. Carrying cases and equipment cases are available in a variety of shapes, sizes, and colors. Some portable cases include handles that retract or wheels that swivel. Others contain an integral stand or legs that fold or hide during transportation and storage. Carrying cases and equipment cases with integral ramps facilitate the loading and unloading of heavy equipment.