Roughly a year and a half ago, EK Water Blocks first introduced its Predator line of all-in-one liquid coolers with medical-grade CPC quick-disconnect couplings. After all that time and plenty of prodding from its customers, the Slovenian water cooler maker will finally let you buy the EK-QDC 10mm couplings by themselves for use in your own loops--a useful tool if you often swap water blocks or radiators in your loop.
Although these aren’t the prettiest quick-disconnect fittings, they’re relatively affordable, easy to use, and have proven to be quite reliable. Releasing them works by pressing the button on the female side of the fitting and then pulling the two parts apart.
Note that although they disconnect easily and their purpose is to stop the flow, you therefore cannot disconnect them when the loop is running (or rather, you should avoid it), and you cannot use them as a drain port.
The EK-QDC 10mm couplings work only with soft tubing that has an inner diameter of 10mm and outer diameters of either 13 or 16mm, with clamps included for both sizes.
U.S. pricing sits at $33, and the quick-disconnect couplings are now available for purchase directly from EKWB.