EK-HDC Fitting is a solid-tube compression fitting, designed for use with solid tubing such as Acrylic, Copper, Stainless Steel or any other type of compatible hard tube. EK-HDC Fitting is a more secure variant of the EK-HD Adapter fitting as it prevents solid tube to be pulled out of the fitting by compressing the rubber gasket underneath the ring. The barb is made of black nickel-plated CNC machined brass while the ring is made of black-chrome plated CNC machined brass and feature quality O-rings. These fittings are fully compatible with EK-CSQ series (45°/90°) angled adapters. Best practice is to install these fittings using Allen Key 9mm (not included, available for separate purchase).