Outfit your semi truck to be Ready for the Road Ahead with ready-to-go warning measures, with the J.J. Keller 18" x 18" Heavy Duty Warning Vinyl Mesh Flag. With a straightforward design, this replacement flag is able to function as a warning signal for emergency situations, work spaces, and roadside hazards. Manufactured with strong and durable materials to withstand rough weather conditions. FleetPride is your First Click in Heavy Duty .