This one is made of two layers of memory foam the bottom one is made of 7 hypo-allergenic high density memory foam and the top one of 3 visco elastic memory foam. It is pretty good combination for the money it costs. Were not gonna mention the advantages of the memory foam over the ordinary spring mattresses again as I think its not necessary. Check the Cal kings specifications: Plush velour stretch cover Soft anti-microbial velour is extremely comfortable as well as durable Staypure removable washable cover completely zips off for machine washing or dry cleaning, ensuring you always have a clean, hygienic sleep environment Solid 3" visco-elastic memory foam comfort layer molds to your body shape and weight for increased circulation and support Reflex 7" hypo-allergenic high density foam provides long lasting durability and support Simply unpack it and watch your mattress expand to fit the dimensions of your bed 20 year limited warranty reflects premium quality and workmanship Queen Dimensions: 80L x 60W x 10H King Dimensions: 80L x 76W x 10H Cal King Dimensions: 84L x 72W x 10H And much more .. Just like with the previous one this one comes with zippered cover which is a very nice feature. This time the comer is velour