Seal N Flex 1 is a low modulus, one component, Class A polyurethane sealant. When cured it will form a tough, flexible seal capable of cyclic expansion and compression movement of 100% (+ 50%) of the original joint width. Seal N Flex 1 is virtually unaffected by normal weathering conditions such as rain, sunlight, snow, sleet, ultra-violet radiation, ozone, atmospheric contamination and pollution. Its excellent weather ability enables it to retain its original properties after years of exposure.