ESI Front Rail Seal XL truck cap EPDM 5.5 ft — fills .488"–1" gap, weather-resistant with 3M tape

ESI Front Rail Seal XL is a 5.5-foot EPDM rubber strip that fills front-rail height gaps from .488" up to 1" between your truck's side bed rails and the cap’s front rail.

When fitting a truck cap or camper shell, uneven rail heights between the truck body and the cap can let in wind, dust, and moisture. The ESI Front Rail Seal XL provides a simple, durable way to bridge that height difference without complex modifications. Made from weather-resistant EPDM and supplied with 3M 4011 acrylic foam tape, this pre-shaped seal saves installation time and stays in place through repeated cap removals.

How do I know if the Front Rail Seal XL is the right size for my truck?

Measure the vertical distance from the top of the side bed rails (including any rail caps) to the front bed rail where the cap mounts. If that gap measures between .488" and 1.00", the Front Rail Seal XL is designed to fill it precisely.

• Use a tape measure at the mounting plane to get an accurate gap measurement.
• If gap is .251"–.487" choose the standard Front Rail Seal (different SKU).
• If gap is .250" or less, install a single full-length ESI cap seal instead of the front rail piece.

What are the product dimensions and materials?

The seal is extruded from EPDM rubber with a nominal cross-section that measures 1.00" wide by 1.125" tall, and it ships as a 5.5-foot length. EPDM resists UV, ozone and temperature cycling, making it suitable for long-term outdoor use.

• Overall length: 5.5 feet (66 inches).
• Cross-section: approximately 1.00" width × 1.125" height.
• Material: durable EPDM rubber for weather resistance.
• Adhesive: factory-supplied 3M 4011 acrylic foam tape for secure mounting.

How is this installed and maintained?

Installation is straightforward: clean the mounting surface, peel the 3M foam tape backing, press the seal into place along the cap’s front rail, and allow adhesive bond time. The tape and EPDM provide a long-lasting bond so you normally won’t need a replacement each time the cap is removed.

• Surface prep: wipe rails free of dirt, oil, and moisture before applying.
• Apply firm, even pressure along the full length to seat the tape.
• No mechanical fasteners required for typical installations.
• Removes and reattaches without needing a new seal in most cases.

Can I use this product with other ESI seals for a complete weatherproofing setup?

Yes. The Front Rail Seal XL is intended to work with ESI’s range of cap seals. Depending on your cap weight and the width of bed rail gaps, pair it with full-length 20' or 23' seals to seal side and rear rails.

• For caps ≤200 lbs, consider Super Cap Seal or Premium Cap Seal options in compatible widths.
• For heavier caps or extra-wide rails, choose XL or Ultra Cap Seal versions.
• To prevent tailgate-side leakage, add the ESI Ultimate Tailgate Seal with Taper Seal.

Who this product is for: The ESI Front Rail Seal XL is made for truck owners installing a camper shell or cap who find a front-rail height difference between the cap and side bed rails of roughly .488" to 1.00". It suits DIY installers and professional outfitters who want a tidy, weather-resistant solution without modifying the truck or cap. If you need a complete, heavy-duty seal system for heavier caps or larger gaps, combine this front rail piece with ESI’s full-length cap seals and the Ultimate Tailgate Seal to achieve a more comprehensive barrier against dust and water. Proudly made in the USA, this seal is best for those seeking a fitted EPDM solution with adhesive convenience and long-term outdoor durability.