These are single use masks, individually wrapped. They start heating up within a couple of minutes of opening the packet.
I was expecting it to stick on to my face but it's got little ear holes and so you just fit it around your head. The problem is that you then can't see anything so I advise setting a timer to go off after 10-20 minutes as this is the amount of time recommended to leave it on.
At first it was a bit underwhelming because I didn't feel like it was sitting close enough to the eyes to do anything and wasn't sticking to my face like I'd hoped. But soon there started to be this weird sensation around my eyes, like a very gentle pulsing. It wasn't painful but I'm not sure it was totally pleasant either. I thought one of my eyes was tearing up slightly but couldn't be sure.
I removed the mask after ten minutes and my eyes were surprisingly damp. I don't really know how it works but they definitely felt steamed, and they had felt pretty dry before I had put the mask on so I feel like it worked!
The effect doesn't last that long but equally my eyes don't feel too dry either so overall I would say it's worth using just to get your eyes back to a normal level of comfort, and take a little down time, maybe to listen to some music while you can't see anything!