This product is the second-generation TOPO cloning kit, which contains the second-generation Topoisomerase, a vector containing the suicide gene ccdB, and a blunt-end factor. Using the second-generation Topoisomerase, with the most suitable buffer, it has higher activity and further improves the cloning efficiency. The efficient connection is completed in 5 minutes at room temperature. Using a vector containing the suicide gene ccdB, when the insert is successfully connected to the vector, the correct expression of ccdB is destroyed, and the host cell can grow normally, otherwise the host cell cannot grow normally, thus achieving a "Zero" background. The addition of blunt-end factor makes this product compatible with TA cloning and blunt-end cloning.