Package Includes: 2 pcs G1/4" Thread Screw-in Water Stopper Plug, with sealed O-ring. Thread Size: G1/4" thread. Diameter: 18 mm/ 0.71 inch, with black chrome plated on the surface. Material: The plug fitting is made of high-quality copper, for rust and corrosion resistance and long durability. Design: the water stop plug is equipped with O-ring rubber gasket for good air tightness, which can prevent internal liquid leakage and oxidation and avoid dust entering the liquid cooling device. Application: Suitable for PC water-cooling system fittings. After the plug screwed in, the liquid in the water-cooling system can be stored for a long time