Open-cell Spray Foam
Made up of cells that are completely closed. One of the benefits of open-cell foam is that it will expand exponentially after it has been applied to the surface. This means it can reach the most difficult to reach places. Open-cell is also really good for soundproofing where a simple application can completely fill an area in between the studs in your wall
Open-cell foam is designed to expand 3” of its thickness when it is applied to a surface. This means you only really need one application for most walls.
Open-cell is also much more affordable.