These wheel chocks are made of strong, durable UV resistant hard plastic. They come in a yellow colour for good visibility. These wheel chocks prevent caravans or vehicles from moving on a site or on the road in an emergency. Chocks are placed for safety in addition to setting the brakes. The bottom surface has a molded pattern to enhance grip with the ground. One edge of the wedge has a concave profile to contour to the wheel and increase the force necessary to overrun the chock. These chocks are also ideal for securing the vehicle at the front wheels when the rear axle is jacked off the ground.