Memory pillows are also called space memory pillows, space pillows, zero-pressure memory pillows, slow rebound sponge pillows, polyether polyurethane pillows, etc. Polyether polyurethane was developed by NASA to relieve the pressure on astronauts, and was gradually used in various medical and civilian products. In particular, pillows made of this material have viscoelastic properties and can adjust to the position of the head and neck. It automatically deforms due to changes in the shape and maintains a tightly integrated position with the neck at all times. In particular, it can fix the head and prevent it from slipping and causing a "stiff neck". It is a kind of pillow made of slow rebound material. It is not to increase people's memory but because the pillow that is often used will form the inherent shape of the human head and neck, so it is called a memory pillow.