These jumper cables are not very good. The wire is Aluminum and the battery clamps are poor quality(steel teeth on one side). You really have move the clamps around on the battery post to get a good connection. The two times that I have had to use them I had to grab a DC current meter to check for current flow and then had to playwith the clamps to get a good connection. Best thing that can be done to this cable set is to cut the ends off and solder on a good set of jumper cable clamps from Napa. By the time you do that you could have just spent $100 on a much better set of jumper cables.