One Pair (Left & Right Side) 07-13 Chevy Silverado/GMC Sierra Crew Cab Lower Rocker Panels. Fits 4 Door Crew Cabs. This is a replacement panel, it is the lower rocker panel. It covers what you see on the outside of the truck when the doors are closed. Some trimming of the edges may be required for the best fit. These rocker panels are stamped for a perfect fit. The bullets are in the correct position just like the original rocker panel. There is a left and right side, these will not fit on either side. You will get the best fit and finished job by cutting out the old rocker panel. Please do not cut out the old rocker panel until you have new ones to use as a guide. Leave about an inch for the new ones to overlap. Made from galvanized steel and are 20 gauge or about 1mm thick. Dimensions: 82.75″ long x 5″ wide x 2.25″ deep. high applications: 2007-2013 chevy silverado 1500 crew cab 4dr 2007-2014 chevy silverado 2500 / 3500 crew cab 4dr 2007-2013 gmc sierra 1500 crew cab 4dr 2007-2014 gmc sierra 2500 / 3500 crew cab 4dr