Super Cap Seal XL dimensions are 2 1/8" Width x 1/2" Height x 23 Length. For beds less than 8ft use Super Cap Seal XL 20ft (ASIN: B00NCCNUJQ). NOTE: To determine if you need to use a Front Rail Seal 6ft (ASIN: B00C0WVV72) measure the difference in height from the trucks side bed rails (including, if any, bed rail caps) to the trucks front bed rail. If the height of the gap is .250" or less install Super Cap Seal XL only. If the height of the gap is from .251" and .487" install Front Rail Seal on the caps front base rail and install Super Cap Seal XL 20ft or 23ft on the caps side base rails. If the height of the gap is extra-large, from .488" to .875" install Super Cap Seal XL 20ft or 23ft on the caps front and side base rails and install Front Rail Seal on the trucks front bed rail. OTHER QUALITY TRUCK CAP SEALS BY Extruded Solutions: "Premium Truck Cap Seal 23ft" measures 2" wide and fills small to medium bed rail gaps, for caps 200 lbs. or less. "Ultra Cap Seal 23ft" measures 1 1/2" wide and fills all bed rail gaps, for caps over 200 lbs and heavier weighted caps. To completely seal out dust and water install patented Ultimate Tailgate Seal with Taper Seal to the tailgate gap and sidewalls. Save and buy the COMBO Pack Super Cap Seal XL 23ft and Ultimate Tailgate Seal with Taper Seal (ASIN: B00BQZ4G3U).