At present, the filling materials of pillows are various, chemical fiber, latex, down, buckwheat husk... Different materials have different rebound time, and the good rebound time is 3-5 seconds. Pillows have a long service life, ranging from six months to three years. After a long time, there will be problems such as loss of elasticity, aging, and mites. Among them, chemical fiber pillows are the most common, but not very ventilated, especially after being used for several months, they are easy to be compacted and deformed. The more they sleep, the more flat they are, and they no longer have elasticity, so they need to be replaced in time. The down pillow is relatively soft and comfortable to sleep, but it is difficult to maintain a certain height. It is recommended to use it with a harder pillow.