For 4.75" I-Beam or H-Beam For Heavy Bags up to 250lbs Fabricated from 3/16" steel plate and powder coated for a durable lasting finish. Mounting hardware is included. Ships Assembled, Made in the USA! The first ever I Beam roller mounting! Roll it out and lock into position or leave unlocked and let the bag move with you intesifying your workout and simulating real fighting situations!! The I Beam Roller is excellent for all style fighters..MMA Fighters, Boxers, Muay Thai Fighters and Kick boxers. For Heavy Bags up to 250lbs!