EK-Torque HDC 16 fittings are EK's new minimalistic 16mm hard-tube compression fittings designed for use with solid tubings such as Acrylic and PETG. With a non-intrusive, yet striking look, and with NO added branding at all. They can be complemented by interchangeable aesthetic color rings. The locking ring prevents the solid tube to be pulled out of the fitting by compressing the rubber gasket underneath the ring. The grooves on the outside allow for easier hand tightening. The compression ring has cutouts in EK Quantum signature shape allowing for the colored aesthetic ring to be shown. The colored rings are available in many colors and are screwed onto the fitting before the compression locking ring. The aesthetic rings are sold separately. The fitting barb and the compression rings are covered with a unique, high-quality finish. Both are made of CNC machined brass and the seal is made of quality rubber O-rings. The base fitting surface is smooth and has no adequate gripping surface, but the inside of the barb is socketed with a 9mm hex Allen key pattern. It's highly recommended to use an Allen Key 9mm (purchased separately) to prevent skin damage to the fingertips while installing the fitting. Technical data: - Thread: G1/4" BSP; 4.5mm male thread length - Supported tube: 16mm OD - The outer diameter of a fitting: 24mm - Installed height: 15mm PLEASE NOTE: Please wet the o-ring using drops of water prior to installing the solid tube. Do not use excessive force when inserting a solid tube or when attaching fitting barbs using Allen Key 9mm It is mandatory to chamfer the edges of cut solid tubes to prevent o-ring damage. EK recommends a 0.5mm x 45 degree chamfer. This product should NOT be installed with any aluminum Fluid Gaming parts! The aesthetic rings are sold separately.