The key revolution brought about by CRISPR is the creation of double-stranded Brakes sequenced. Specifically, with CRISPR, scientists can create double-stranded breaks at virtually any site in the genome. To repair the double-strand cracks generated by CRISPR, there are two main mechanisms nonhomologous end joining and homology-directed repair, also known as homologous recombination. With nonhomologous end joining, the ends of the double-strand breaks are simply reconnected together. This process is highly error-prone, introducing mutations, insertions, and deletions and, in many cases, resulting in gene knockout. Homology-directed repair, on the other hand, utilizes a repair template where desired changes are flanked by left and right homologous sequences. Through homologous recombination, the desired changes are incorporated into the genome. The CRISPR Knockout Knockin kits utilize the homology-directed repair system planned.