Instruct: Classify Amazon reviews into positive or negative sentiment
Query: I wish I could give it negative stars!

I've been pumping for six months and have only once gotten a blocked duct. It was annoying but quickly emptied. After only 45 minutes of wearing one of these shells to protect a cracked nipple, five of my ducts were blocked! By that evening I was able to empty four of them, but one stayed blocked and by the next morning it had turned into mastitis. It was awful. I threw these away as soon as I healed up. Do not use these!!!