EK-HD Adapter Female is a solid-tube female type fitting, intended to be used with solid tubing such as Acrylic or Copper tube.The product is made of machined brass with quality O-rings. These adapters are fully compatible with EK-CSQ series (45/90) angled adapters.Technical data:- inner thread: G1/4\" BSP- supported tube: 12mm (OD)- outer diameter of a fitting: 18.7mm- installed height: 11mm- compatible tubing: solid Acrylic-, Copper-, Brass- or Stainless Steel tubeROHS Compliant!