Features: Premium 3/4 inch straight copper couplings with sweat joint design ensure leak proof HVAC connection, featuring oxygen free copper construction for best thermal conductivity and corrosion resistance. Accuracy engineered with 19mm inner diameter and 0.9mm wall thickness, these polishes copper fittings eliminate burrs for smooth installation in air conditioning and refrigeration systems. Essential for HVAC technicians and plumbing professional requiring strong , maintenance free copper pipe connection in commercial/residential climate control projects. Ideal for sweat soldering copper tubing in split units, heat pump installations, chill water pipelines, and industrial refrigeration maintenance applications. Each set includes 4 identical copper pipe adapters meeting ASTM B280 standards, designed for permanent corrosion resistant joints in pressurized HVAC/R systems up to 400 . Specifications: Material: Copper Inner diameter: 19mm/1/4 inch Outer diameter: 20.8mm/0.82 inches Thickness: 0.9 mm/0.03 inches Total length: 25.4 mm/1 inch Package Includes: 4xCoupling Fittings note: 1.Please allow 1-2cm errors due to manual measurement, make sure that you do not mind before you order. 2.Due to the difference between different monitors, the picture may not reflect the actual color of the item.