Fiberglass Supply Depot 4 Lb. Density Expanding Pour Foam, 2 Part Polyurethane Closed Cell Liquid Foam for Boat and Dock Flotation, Soundproofing, Filling Voids, and Insulation (1 Gallon Kit)

It's it reacts very fast, especially when it's hot out. But it is very solid, takes about 10 minutes to set up completely. It works perfect for fence posts.

Awesome stuff, I used it to fill holes used from animals going under my cement driveway and walkway. Fantastic results and hardens like a rock

Petrol breaks this product down and absorbs petrol

It worked perfectly to replace floatation foam in a boat

It arrived broken, but they replaced it. I give it 5 stars because the product is super good for my boat; it's excellent. Thank you.