Leaded. Because of Laws etc new systems are recommended to use lead free but with lead free its not that good - repairing jobs leaded solder is recommended https://www.amazon.com/gp/product/B00068IJPO/ref=as\_li\_tl?ie=UTF8&camp=1789&creative=9325&creativeASIN=B00068IJPO&linkCode=as2&tag=micromage0f-20&linkId=80417c267af52194f27e63a431d3a151