Instruct: Classify Amazon reviews into positive or negative sentiment
Query: Spark Plugs are not fully firing

I received these "Spark Plugs" along with a set of the Koss KSC75 headphones. These earphones sound very muffled. The price was great but I wish that I ordered two sets of the KSC75 instead of getting the "Spark Plugs". Do not get both, you will be disappointed by the Spard Plugs.