EKWB EK-Quantum Torque STC-12/16 Compression Fitting for Soft Tubing, 12/16mm (7/16" ID, 5/8" OD), Black, 4-Pack

Great fittings, but do yourself a favor and don’t pay the Amazon tax on these, go direct to the manufacturer.

Ordered 2 packs of 4 for 8 total and one slipped QC that doesn't even thread into the radiator or my CPU block. It looks pitted pretty bad, even on the threads. The other 7 are high quality like something you'd expect from EKWB. Already ordered the replacements