PU33 is a low density open cell foam and weighs only 33kg/cm3. Compared to other PU foam PU33 is considered “high density” polyurethane foam. It is a soft foam but is reasonably heavy duty for long lasting use. This foam’s higher density renders it more resistant to breakdown and degradation, and its increased firmness aids in the casing of frequently used but delicate items that must be packaged snugly, like instruments or technical equipment. It can also serve as entry-level soundproofing.