EKWB EK-ACF Fitting 10/16mm - Black EK-ACF Fitting (Advanced Compression Fitting) is a soft-tube compression fitting designed for use with flexible soft tubing such as PVC, EPDM, Norprene, or silicone Use an 8mm allen key to tighten the fitting to ensure a perfect seal every time and to prevent skin damage to the finger tips that competing products may cause Compatible Tubing Size: 10/16 | 3/8" ID - 5/8" OD Color: Black G1/4 Thread