ESI Super Cap Seal XL 20ft EPDM Rubber – Truck Cap Seal, Made in USA

Overview

The ESI Super Cap Seal XL 20ft is a heavy‑duty EPDM rubber seal designed to bridge the gaps when mounting a truck cap or camper shell on trucks with extra wide bed rails. Built for durability and long service life, it is made in the USA to professional standards. The 20ft length can be trimmed to fit varying bed widths, offering flexibility for different vehicles or cap sizes. For eight-foot beds or caps that require more than 20 ft of seal, consider the XL 23ft option (ASIN: B00BNGBXOC).

Why it stands out

• 20ft length covers wider bed rails and heavier caps (over 200 lbs) without frequent replacement.
• Fills bed rail gaps completely, helping reduce dust, moisture, and vibration transfer; the kit includes everything needed for a complete install.
• Premium automotive EPDM rubber provides strong compression resistance and long service life, favored by professional installers over PVC or foam seals.
• Designed to tolerate routine cap removal without replacing the seal each time, offering long‑term maintenance convenience.
• Made in USA for quality control and reliable availability.

Sizing and installation guidance

Use the gap height method to decide if a Front Rail Seal is needed in conjunction with the XL seal. Measure the difference in height from the truck’s side bed rails to the front bed rail (including any caps).

• Gap up to 0.250 inches: Install Super Cap Seal XL only on the cap’s front base rail.
• Gap from 0.251 to 0.487 inches: Install Front Rail Seal on the cap’s front base rail and install Super Cap Seal XL 20ft on the cap’s side base rails.
• Gap from 0.488 to 0.875 inches: Install Super Cap Seal XL on both the cap’s front and side base rails and install Front Rail Seal XL on the truck’s front bed rail.

If you’re unsure, this approach helps tailor the seal setup to your vehicle. The kit includes the seal, butyl tape, alcohol pads, and detailed instructions to guide the installation.

Practical notes

• 8 ft beds and caps that require more than 20 ft of seal can use 23 ft XL (search ASIN: B00BNGBXOC).
• Trim the 20 ft length to fit smaller front bed rails for a precise fit when needed.
• All components are designed for ease of use and long-term reliability on the road.

In real-world use, the XL 20ft seal supports a secure fit between the cap and the truck bed, helping to reduce movement and provide a robust barrier against the elements. The included butyl tape and prep pads help prep surfaces for a clean bond, while the EPDM material stays flexible through temperature changes and road conditions.