Instruct: Classify Amazon reviews into positive or negative sentiment
Query: Terrible Garbage

I bought this to increase both speed and vertical. IT DIDN'T DO ANYTHING. All it did was wear out and make my shoes have disgusting stains on them. They were under my soles yet the rubbish excess from them stained the top of my shoes. They wore out in 2 months and did absolutely nothing. The BIGGEST waste of $35 in my entire life. Please do not buy these.