Not as strong as I thought. My mom's phone still lasts and mine stopped charging the phone a month ago. I didn't want to bother but then my mom told me her phone wasn't charging well and neither was her tablet. I then decided to accept their offer to fix the problem and was happy with the customer service. Two wires arrived free of charge two days ago and so far so good. They worked great initially and I hoped they would stay that way for a very long time. I'm very excited to see how they work with our devices. Those who leave a low rating will try to work with you, which I think is great customer service. Thanks again to everyone involved/workers at the Nancy Shop. Review from 12/04/2018: Unfortunately my wire died a week ago. Charging crept in and it took almost four hours to charge my devices to just 5%. Currently the other cable is used by my mother and it works. I chose Anker and bought two wires for $10. The length isn't as long as theirs but they don't seem to last at all. Unfortunately this seller is very friendly and I was hoping they would last a long time. Hopefully the one my mom is using will still work, but I had to throw mine out and replace it with another manufacturer/company.