The size of the eye mask is shown in the photos. ^ ^ It usually fits right over the eyes. It has soft elastic, so you can drift right off to sleep... The gray part is satin fabric and very soft. ^ ^ Terahertz is an artificial mineral that emits terahertz waves, electromagnetic waves that vibrate one trillion times per second. Terahertz waves have properties between radio waves and light, and are attracting attention among people interested in health and beauty, as they are said to have a positive effect on blood circulation and cell activation. It is expected to improve blood circulation, activate cells, improve coldness, recover from fatigue, and have a relaxing effect. It relieves eye strain and relaxes the tension around the eyes. Purchased from a store that handles medical-grade terahertz. Natural stone Power stone Health goods