Koolance patented quick disconnect no-spill coupling with automatic shutoff. 10mm (3/8in) ID, 16mm (5/8in) OD male straight connection with compression fitting. It will only fit a Koolance QD3 female quick disconnect. After pulling the ring on the female QDC side, the quick-disconnect fittings will separate. Liquid on both sides will be automatically obstructed with approximately 0.2ml freed.