This lock washer is used frequently for a number of applications on power yard equipment. The size, 5/16, is the default for many small engine housing and manifold applications. Lock washers are used with machined bolts to fasten engine blocks to the housing of the equipment being used. The compressed washer is able to handle the constant vibration of the small gasoline engine without losing the seal between the screw or bolt and the housing. Typically these lock washers only need to be replaced when they are misplaced during repairs or when the screws that attach them have to be chiseled or cut away, meaning the washers are destroyed as well. These OEM certified replacement washers have been manufactured to the same specifications as the originals they are replacing. In addition to lawn mowers, lock washers of this type and size are frequently used on blowers, lawn tractors, cultivators, snowblowers, and trimmers. Brands compatible with this type of washer are Murray, Husky, Poulan, Bolens, Yard-Man, Cub Cadet, Troy-Bilt, Yard Machines, MTD, and Ryobi.