The heavy duty Model 2500 door has become the standard of all commercial sheet doors. Backed by a one year warranty, we manufacture each door with high quality materials that will last for years. The features and general specifications of the 2500 door make it versatile and easy to install. Find each of these below: Utilizes 12” drum wheel Maximum opening size of 18’ wide x 18’ high (324 sq.ft.) Push-up, hand chain and electric operations