For truck caps that require more than 20ft of seal use Ultra Cap Seal 23ft. Easily trims in half to fit trucks with smaller width front bed rails. NOTE: To determine if you need to use a Front Rail Seal 6ft, measure the difference in height from the truck's side bed rails (including, if any, bed rail caps) to the truck's front bed rail. If the height of the gap is less than .488" install Ultra Cap Seal only. If the height of the gap is extra-large, from .488" to .974" install Ultra Cap Seal 20ft or 23ft on the cap's front and side base rails and install Front Rail Seal XL on the truck's front bed rail. Made in USA