The Peterbilt 579 And 567 NGP High Roof XL 4 Inch Conversion Kit is a practical and efficient solution for enhancing your Peterbilt 579 or 567 NGP High Roof XL models. This kit includes a 4-inch cab extender, pre-assembled fiberglass panel, pre-installed bracing, and a window for added convenience. The pre-installed sound deadening core ensures a quieter ride, while the CNC cut and drilled panel guarantees a precise fit. With a class A gel coat finish and all necessary hardware and sealer included, this kit is a comprehensive solution for upgrading your Peterbilt.