Double urethane transit car railroad wheel chock features a resilient double chock with fiberglass handles for use with transit and passenger cars. Not recommended for heavy freight cars or where excessive vibration takes place. For flush rail on flat track only. Do not use on grades. Rail surface must be clean. Do not install this product on oily or greasy rail - product may slip. Tension cord is sized to fit minimum 28-inch diameter wheel and can be stretched to accommodate up to a 36-inch diameter wheel. Product of Aldon® Company.