Manufactured for low and medium pressure applications, they should not be used when excessive vibration or tube movement is experienced. Assembly does not require flaring or soldering. To make connection, place nut and then sleeve over tubing and insert tube into body of fitting as far as possible. When nut is tight the wedging action of sleeve between body and nut create a tight leak free connection. Recommended uses: copper, brass and aluminum tubing Material: brass (check valve has steel components) Working pressure: dependent on temperature and type of tubing Application: air, oil, water and natural gas lines