Butyl: RetroRubber (Black)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! Purpose: Until now, the only other butyl ropes on the market were meant