Instruct: Classify Amazon reviews into positive or negative sentiment
Query: Poor design

I purchased these cuffs after testing a set of the steal cuffs without any issue. I though these cuffs would be lightweight and efficient. I found these cuffs are lightweight but the black plastic has a raised edge inside where the single bar passes through the double bar restricting it's free movement. I thought I could shave down the plastic to allow the single bar to pass freely but now the cuffs are unusable. I bought two pair, they both have these flaws.