The included Control Template and Primer mix contains two plasmids that when amplified will produce amplicons with and without a 10 bp insertion. The primers included in this mix will amplify a ~600 bp region around this insertion. After denaturation and re-annealing of these PCR products, some will form heteroduplexes. The T7 Endonuclease I will detect the heteroduplexes and cut them to yield fragments of  ~200 bp and ~400 bp. The fragments can be detected by standard agarose gel electrophoresis or by using fragment analyzers.