Very good quality. They were actually difficult to crimp as they are much harder than regular Auto Zone materials. This gives me more confidence when connecting cables (which I hate and will rework and run new cables whenever possible), especially cables that carry a lot of load. In my automotive career, I've often seen how corroded or badly connected wiring causes nightmarish search and repair headaches - and even burns cars to the ground. Wiring is like brakes. Do it right or have someone do it right if you don't have the skills and experience. Safety first.