Instruct: Classify Amazon reviews into positive or negative sentiment
Query: No bass at all

Even the spec says "Frequency response: 14Hz - 24kHz", there is no bass. The core is very hard and thin. They will stay on ears (all sizes), but definitely not worth more than $10. Sony MDR-J10 h.Ear Headphones with Non-Slip Design (Blue) has better sound quality and less than $10. I like other Panasonic products, but this one ruined their reputation.