Instruct: Classify Amazon reviews into positive or negative sentiment
Query: Graco Car Seat Undermat

My husband and I purchased these, we thought they would be perfect for under our Graco car seats. We had the car seat bases professionally installed in our cars, and the professionals told us that we couldn't use the undermats. The car seat base slides around and isn't secure with the mat underneath it. I was told this would be the same situation for a toddler car seat.