High density foam has a compression rate of 33lbs. Higher density foam will remain responsive longer, it features the perfect amount of cushioning and stiffness. Higher density firm quality foam is designed for heavy traffic and high use applications. This 3" high density foam ( 3"x 24" x 72") provides 3" full inches of high density foam thickness size : 3" thick x 24" wide 72" long color : white density: 2.4 lbs (high density). 100% recovery rate fire retardant durability : durable, high density foam suitable for long-term use. Density and compression indicate the softness and longevity of foam. Compression = firmness compression (not density) is what determines firmness. If you don't want a cushion that's hard as a rock or a mattress that sinks when you sit on it, you have to check the compression. Compression means the number of pounds necessary to compress a piece of foam 25% and still bounce back to the original thickness. For example, a 4" thick piece of foam that requires 35 lbs. To pack it down 1" and have it return to its full 4" thickness has a 35 lb. Compression rating indention load deflection. Foam sheets are sold per sheet - not per yard and rolled for packaging. Packing, shipping & cutting - foam packages need to be opened immediately once you receive the package.