I wouldn't know what to do without this eye mask! In fact, I own two.
You secure the eye mask in place with a velcro seal, so it never feels tight. (Poorly designed eye masks makes you feel as though blood is not flowing to your eyes properly.) The material for the mask itself is also thick enough to block the light properly. (Believe me, some masks don't do what they are supposed to!)
The only thing I don't like about it is the material for the mask. It feels slightly rough on my skin, so I normally use a handkerchief between the mask and my eyes.