I would NOT describe these pillows as true "memory foam" as they are on the firm side. But they have good resiliency and do not get "squooshed" like softer flimsy pillows. If you sleep on your side you will LOVE these pillows. Even though they have the contoured edges to allow the pillow to rest at a slight angle, I find them a little too stiff. to comfortably sleep on my back.
4inches of compacted memory foam makes a firmer than firm pillow. A thermafoam salesman told my friend to stomp on the pillows for a minute a day until they soften up. Tried this didn't work. May have to use them as seat cushions for awhile to break down their firmness. Also queen size pillow cases do not fit them well. four inches is not deep enough for typical pillow cases.Still a good buy for the product.