Instruct: Classify Amazon reviews into positive or negative sentiment
Query: one of the worst yet

These have to be some of the worst electrodes I've used to date. The adhesive is only good for 1 use, maybe 2, even with cleaning. The edges come up off the skin, the gel on one actually peeled right off the edge when I was removing it per manufacturer instructions after 3 uses, and after just 1 use I don't get the same level of relief, most likely because the gel just wears right off or thins to a negligible amount after a single use. This was a waste of $20.