Ergonomic design - Cervical pillow has two heights (4.7"/4"), in line with ergonomic engineering, so you have more options. Reduce more neck pain, back pain or headaches and tossing and turning, and no more waking up stiff and tired so that your health are back on track.3-5s Slow-rebound Foam - A high-tech material originally designed for astronauts to help relieve the stress during takeoff, landing and flight. Thanks to the unique pressure-relieving properties of slow-rebound foam, slow-rebound pillows allow the head to rest in a natural, stress-free position.Soft But Firm - The high-density memory foam makes the pillow soft and firm, allowing the pillow and the neck to fit perfectly and relieving the pressure on the neck.Super AirCell Cooling System - Perforated design that allows more air to circulate for a cooler sleeping environment.100% Satisfaction Guarantee – Every people may have different needs for the firmness of the pillow because of the differences in height, weight and ages. If you feel like the pillow is not suitable for you, please contact us for a full refund.