I had to really work to get these to clamp down since there was no split along the neck. However, once i did muscle it closed, it does feel very secure on the wire. I used it on 4AWG marine cable for a boat battery setup, and I feel confident that the cable is not going to slip out of the ring connector. Would have felt a little better about a bit thicker insulation on the shrinkwrap, but it would be too far to say that it was bad at all.