A hex key, also known as an Allen wrench, is a small tool used to drive screws and bolts with a hexagonal socket. It typically has a simple L-shape, allowing for easy grip and leverage. Hex keys come in various sizes to fit different screw types, making them versatile for many applications, from furniture assembly to bicycle repairs. These tools are commonly made from steel or other durable materials to withstand torque. Hex keys are often included in furniture assembly kits, alongside items like screws and bolts, and are essential for tasks requiring precise fastening in tight spaces.