Running Board Extenders Complete the look of your Boss Running boards on your Chevrolet or GMC Truck. Boss Rear Extenders have a bold four-inch facing for a rugged big truck look! They are made from NeveRust stainless steel that won't rust even under harsh conditions. Boss Rear Extenders begin behind the rear wheel well and extend to the bumper area. Customized mounting bracket for each application. Lifetime Warranty. No Drill Installation. Sold in pairs. Made in the USA. Be the boldest tricked out truck on the road!