Seacast™ is a syntactic material; a mix of proprietary resins & ingredients with reinforcement recycled fiberglass fibers. We have been using Seacast™ to replace transoms, stringers, inboard/outboard engine mounts and decking. Others have also been using it to build the porch/patio decks on their homes. Seacast™ has a shelf life of uncured stability that we warranty for 6 months. Seacast™ uses chopped reinforcement recycled fiberglass where others use ceramic spheres. In comparison fiberglass strands provide superior tensile strength better than ceramic spheres. Pound for pound, we dropped a 20 lb. weight from 10 feet creating 200 ft lbs of force. The difference is we dropped it once on the competition and they split and broke on the first drop. We dropped it 20 times on the Seacast™, which resulted in just minor cosmetic damage.