Flat round washers are flat and smooth and are primarily used with bolts and nuts to provide a larger bearing surface, which distributes the load evenly over the surface area, so it isn’t damaged. They are also used to ensure that the nut is pressed against a smooth surface, which reduces the chance that it will gradually loosen.Flat Washers are circular with a center hole, are most commonly used to meet a broad range of fastening applications. They increase a nut or fastener's head bearing surface, spreading the clamping force over a bigger area. They are useful when materials are oversized, soft, or have irregular shaped holes.