Our DNA ligation kit for long fragments is a powerful tool for cloning long DNA fragments spanning 2 kb to over 10 kb in length. This kit contains an optimized ligase/buffer system that enables ligation of long fragments without the need for extensive techniques or special expertise. It is especially well-suited for BAC library construction. Compared with other systems, the TaKaRa DNA Ligation Kit LONG results in insertion efficiencies up to 50X higher for high-molecular-weight DNA fragments ranging from 2 kb to 18 kb than other kits. In addition, this kit also enables fast and easy ligation of smaller-sized DNA inserts.