EK-Quantum Torque HDC 16 fittings are EK\'s new minimalistic 16mm hard-tube compression fittings designed for use with solid tubing 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, and are an ideal choice for anyone and a perfect match with EK-Quantum series products.Torque series fittings are part of the EK Quantum Product Line that emphasizes minimalistic, elegant design, and performance. For those who want to stand out!EK-Quantum Torque series products received the prestigious iF Design Award. A robust and industrial aesthetic sets the Torque family apart by highlighting the precise manufacturing processes used to create them. In addition, enthusiasts can add a unique color ring to give a personal accent to the fitting line. The Torque family of fittings offers a secure and modular system of connections between liquid cooling components and tubing within a PC. Quantum Torque series products cover angled adapters, rotary and static extenders, splitters, G1/4\" plugs, drain valves, fittings, and much more. The locking ring prevents 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 black nickel finish. Both are made of CNC machined brass and the seal is made 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. Please, be advised not to use excessive force when attaching fitting barbs using Allen Key 9mm in order to prevent damage to other liquid cooling products! These fittings are guaranteed to be compatible with all other EK Water Blocks liquid cooling products. If you are interested in buying spare outer o-rings for the G1/4\" seal, you can find them here.Technical data:- Finish: Black Nickel- Thread: G1/4\" BSP; 4.5mm male thread length- Supported tube: 16mm OD- The outer diameter of a fitting: 24mm- Installed height: 15mm- Compatible solid tubing: Acrylic, PETG, Copper, Brass, Stainless Steel