PROTECTION: Is priceless! When you're putting together a set of high-end headlights, the last thing you want is moisture in 'em the first time it rains outside. After many years sealing headlights with spools of butyl meant for windshields and sunroofs; we've finally got a product that puts OEM-style sealant designed specifically for use in headlights, and indeed it works well! Until now, the only other butyl-ropes on the market were meant for "universal" applications, and true headlight butyl only came in blocks that were nearly impossible to apply without industrial machinery. Morimoto's Retro-Rubber is designed specifically for resealing headlights, not windshields, sunroofs, etc. At room temperature, the RetroRubber has a much harder consistency compared to OCI Butyl glue. Given the "fingernail test" it will harden up just like any OEM Butyl Rubber glue once cooled. Not all headlights are created equally! Whether your housing was originally sealed with black or gray glue, the RetroRubber has you covered with options. Available in....you guessed it, black or gray... you won't have to settle for a mis-match. Each roll comes with approximately 4M of glue, which is easily enough to re-seal two or more large headlights. Simply stretch it out until it's the perfect thickness to fit inside the headlight channel, cut it to length, rough-fit the lens back onto the housing, heat for at 265F for seven minutes, and compress the housing back together. Done! fog light housings too!