100 Pack of 21mm High Visability Yellow Safety Check loose wheel nut indicators Easy Installation: Simply push the Safety Check indicators on to your lug nuts in a consistent pattern and you are done. Loose Wheel Nut Indication: To determine if you have a loose wheel nut, simply look down at the indicators to see if any of them are pointing in a different direction from the rest. Overheating Wheel Indication: The melting point on the Safety Check loose wheel nut indicators is 240 degrees Fahrenheit which will provide an additional safety check for your wheel and brake temperature. If the Safety Check indicators warp or melt, your brakes or hub assembly may be overheating and need service. Size: These Safety Check loose wheel nut indicators are designed for 21mm wheel lug nuts on trucks, trailers, commercial vehicles and more! ASIN B0CZ3FYTNP Brand TYK Industries Item Weight 5.9 ounces Manufacturer TYK Industries Product Dimensions 0.83 x 0.83 x 0.83 inches Manufacturer Part Number TYKSC21YEL-100