Instruct: Classify a given Amazon review into positive or negative sentiment.
Query: Grind Guards are Great

I liked this particular brand of night guard better than the one I bought before. However, I only gave it 4 stars because you really have to pay attention to the sizing. And that is where the minus one star comes in. I don't know HOW anyone could gauge their size really. It says if you are "this" tall and weigh "this" amount then "this" size is for you. It didn't work for me. I should have listened to my dental hygienist sister as she once told me I had a small pallet. Ah well. I'll try again. The BEST part about this night guard is that it's CHEAP! And it's even easier to mold than the last one I bought on Amazon. Just follow the instructions to a T and you'll be fine.