Product Information: Medium Density foam has a compression rating of 33 lbs. It features the perfect amount of cushion and fill. It is soft yet still maintains its firmness for an individual to sit on it without compressing the foam to much. (Medium quality foam is designed for heavy duty and intensive use applications.) Density: 1.5 / 100% Recovery Rate / Fire Retardant / 33.lb Compression = Firmness Compression (not density) is what determines firmness. If you don't want a cushion that is rock hard or a mattress that sags when you sit on it, you need to check out the compression or ILD number. Compression means the number of pounds required to compress a piece of foam 25% and still bounce back to the original thickness. For example, a 4 inch thick piece of foam that requires 35 lbs. to pack it down 1 inch and have it return to its full 4 inch thickness has a weight of 35 lbs. Compression rating or ILD -Indention Load Deflection. Usage: Great for oval and round poker tables, furniture cushions, boat cushions, car cushions, foam mattresses, bedding support, and all other home and commercial upholstery applications. Foam packages should be opened immediately once you receive the package. Do not let the foam sit unopened for more than 1 week. Do not open with a box cutter. Use a pen or pencil. Start by making a small injection and break it up from there. Durability: Will last 7-10 years Care Instructions: When unpacking, allow at least 2 days for the foam to breathe in order to regain its original size and shape.