Wheel-Checks are a loose wheel nut indicator that can identify loose wheel nuts with a simple visual inspection. When the lug nuts are properly torqued to specs, the Wheel-Checks are then placed on the lug nuts in a uniform pattern. If a wheel nut has loosened, the Wheel-Check will become out of sequence. It will be visible when the driver does his walk around check. The wheel can then be serviced. Sizing: Be sure to measure from flat to flat (refer to image) to determine accurate size.