Flex Seal Liquid is a versatile product that can be used on a wide range of surfaces such as concrete, glass, brick, stucco, masonry, wood, copper, plastic, tile, fabrics, wires, vinyl, fiberglass, ceramic, porcelain, metal, aluminum, and natural stones, foam, asphalt, EIFS, TPO, PVC, EPDM, CSPE, Hypalon polyurethanes, and more. Users recommend testing on a small area before application. The product works best above freezing temperatures, can seal leaky ducts, and provides a good grip on outdoor surfaces. It is available in four colors - White, Black, Gray, and Clear.
The product can fix various areas around the house, including sealing gaps outdoors, fixing leaks, and sealing above-ground pools. Customers recommend using the product on small cracks, and it may not be suitable for large areas or deep holes. A reviewer used it to seal a masonry joint that ran the length of the outdoor deck to prevent water leakage, which was successful, and boards the product as a cheap and easy fix to a big problem.