Extension for Midwest Steel Pet Gates come in 6-inches or 11-inches. MidWest Pet Gate Extenders - White matches perfectly with your MidWest Glow in the Dark White Steel Pet Gate. Choose the gate height relevant to your gate (can be either 29 inches or 39 inches), and then choose the extension length you want to achieve. The gate itself fit spaces from 29.5 to 38 inches wide (74cm to 96cm). As a guide: 6-inch Extensions will add an additional 6 inches or 15cm, while 11-inch Extensions will add an additional 11 inches or 27cm. Choose to extend your current gate to a maximum of 54 inches wide.