The 10 In. x 3-1/4 In. to 4 In. Stack Boot by Master Flow is a high-quality galvanized steel ducting accessory designed for heating and cooling systems. With a manufacturer's warranty for free from manufacturer defect at time of delivery, you can trust in the durability and reliability of this product. The stack boot comes in a convenient 4-pack size, making it easy to install and ensuring a secure fit for your ducting needs. Made with strong and sturdy materials, this product is a must-have for any home or commercial setting looking to improve their heating and cooling systems.