The max wide that alligator clips open is 10mm. Voltage: 1500V;Current:15A. 39.3 inches wire with nice rubber insulation cover and the alligator clips made of copper. The clips make it easier to grasp the item you are trying to read, allows hands-free testing, great for remote spaces. The wide for alligator test clips robust enough to be useful for testing circuits on your vintage cars, trucks and motorcycle, etc This really is a great set of Jumper or Tester wires. High quality thick cables. Excellent leads that can be used to do a variety of electronic testing. It will works as intended in conducting electricity! These are good sturdy leads with thick wire and nice clips. The clips had insulators to reduce the possibility of accidental shorting. Good quality leads that work great for moderate to low current testing. These wire are good for up to 15 amps maximum. They are fine for basic electrical testing for things like automotive accessories, as long as whatever you are testing uses