Instruct: Classify Amazon reviews into positive or negative sentiment
Query: Works like a charm

This is the only sleep mask I've ever used, and I bought it because it has a lot of great reviews. The people aren't wrong. This mask is extremely comfortable and very effective at keeping out the light. The only problem I have with it is the velcro straps that adhere at the back of the head. The velcro always manages to get tangled in my hair overnight, and it's painful to yank my hair out of it. I would prefer that the mask instead had a band that would slip over the head, but that's minor. The mask really is very nice and so comfortable to use.