As an industrial user, I highly recommend these plastic inserts for finishing off square tubing. They fit snugly and securely into the ends, providing a smooth and professional-looking finish. As a result of using this product, I found that it helps protect the tubing from rust and other damage. The only downside is that they are slightly difficult to remove if needed, but that is a testament to their secure fit. Overall, a great purchase for anyone in the Industrial and Scientific field.