Features Automotive grade butyl sealant. Easy to work with, no sticky mess. Standard black color 20 feet long (enough to reseal two large headlamps). 7mm diameter, designed to fit directly in headlamp channels. Overview Easy to work with.Properly reseal any headlamp or tail lamp and protect against moisture ingress with Diode Dynamics Butyl Headlight Sealant! This new and improved sealant rope was designed specifically for headlamps, with a firmer composition than auto-store windshield glue. This makes it easy to work with, without causing a sticky mess. Each roll comes with 20 feet of butyl, enough to reseal two large headlamps.