This Tip and Roll bleacher is 21 ft. long with 3 rows of seating for sporting events. Made to roll in place for convenience and comes with a set of four no marring 5" casters with brakes preventing any markings on the floor. Made with 2 x 10 aluminum planks and aluminum frame with strong joints. This bleacher seats 42 adults and is only 30 inches high with 7" rise between each row. Please check your local building codes to determine required specifics for portable bleachers. Guardrails and additional foot boards are available upon request. Call our friendly staff for any questions.