Flap wheels are abrasive tools used for sanding and finishing surfaces. They consist of multiple overlapping flaps made from abrasive materials, such as aluminum oxide or silicon carbide, attached to a central hub. These flaps allow for flexibility and adaptability, making flap wheels effective for contouring and smoothing various shapes and materials, including metal and wood. Typically mounted on a power tool like a die grinder or sander, flap wheels come in various sizes and grits to suit different applications. They are popular in industries such as automotive, woodworking, and metalworking for their ability to provide a consistent finish while minimizing the risk of damage to the workpiece.