BAL 28000A  Tire Lock Chock Extend or retract both front and back chocks by turning the large center wing nut for a custom fit between tandem tires Stabilizes both front and back tandem wheels Zinc-plated steel resists rust Diamond tread design provides a sure grip Adjusts from 15 1/4" to 22 1/2"L. 4"H x 3 1/2"W