Quality clamps have serrations inside the barrel to ensure a good grip on the wire, this is not the case . Since I was using 16 gauge wire, I was hoping that stuffing it with wire would make it unnecessary. I've tried using the correct crimping tool and went through with a slight tug, but many failed even with moderate force. It ended with a vice grip gorilla smashing them to get the job done. At this price I understand the cost saving measures, just make sure it doesn't put a strain on your connections.