Brand new 1/2" X 1/2" female npt inline air compressor check valve. This valve is brass constructed, and is 3 1/16" long. The inline check valve design is made for applications where a normal in tank check valve will not work. This valve can be installed anywhere in the discharge line of the compressor before the air goes into the tank. This valve has a 1/8"port in the side for a un-loader line, If your compressor does not have one then it can be plugged. The inlet side of this valve is stamped with the letters IN, it is very important that you get it in the right direction. If not installed correctly it can do damage to your compressor.