SET uses a technique called handprinting - which is based on earlier techniques known as "Shingling" that have been used to filter junk e-mails - to seek out files that contain some of the data needed by the one a file-sharing program has requested. The SET system computes a handprint for each file, and can take chunks of data from files which are both identical and similar to the one being searched for. The lower similarity ranking that SET searches for, the more sources for that data are likely to be found. The extra overhead of locating these sources does not out-weigh the benefit of using them to help saturate the recipient's available bandwidth. Indeed, exploiting similar sources can significantly improve download time.