Gibson Assembly Cloning Kit has been used to clone a 15 kb DNA fragment into a 5.4 kb plasmid in E. coli, totaling up to 20.4 kb in length. For assembled products greater than 15 kb, NEB recommends NEB 10-beta Competent E. coli (High Efficiency, NEB #C3019) or NEB 10-beta Electrocompetent E. coli (NEB #C3020).