Extang Tool Box Tonneau Cover - 10% and Ships Free from Extang in 24 Hours. This is a great solution for truck owners who already own a tool box, no matter what brand. The tool box tonneaus fit most standard tool box sizes. Simple, quick and easy do-it-yourself installation. No drilling. No damage to truck bed. Protects finish. Extang engineered anodized L-Channel™* is an adjustable sealing system that easily bridges the tool box-to-tonneau gap for a perfect fit. The L-Channel also provides for rain drainage. All-climate tonneau design that's fully adjustable for easy use in cold weather climates. Famous Extang engineering, quality workmanship and excellent customer service are behind every product we sell.