A locking element for a connector configured to connect two components of a fluid transfer system and a connector that comprises the locking element are described. The connector comprising the locking element is configured to provide continuous fluid channels between a first component and a second component of a fluid transfer system, the fluid is a hazardous drug and the connector is designated for safe and contamination-free transfer of said hazardous drug from first to second container while isolating the needle tips and causing no dangerous and harmful leaks.