1/4" Female NPT Inlet X 1/4" Male NPT Outlet. (1/4" NPT measures 0.505" outside thread diameter linear inches) 1/4" NPT General purpose filter protects tools and equipment by removing most solid and liquid contaminants This may include dust, dirt, pipe scale, rust, liquid water and bulk oil. A 40 Micron filter element removes the smallest of particles. Help prevents costly damage to air tools caused by rust, scale and moisture 300 PSI Max input/output pressure. Connects directly to your 1/4" NPT air hose or quick coupler. Light weight aluminum body, Easy to install In-Line Air Filter For Pneumatic Air Tool, 300 PSI MAX , 1/4 Male outlet x 1/4" Female inlet. Filter protects tools and equipment by removing most solid and liquid contaminants. This may include dust, dirt, pipe scale, rust, liquid water and bulk oil. A 40 Micron filter element removes the smallest of particles. Help prevents costly damage to air tools caused by rust, scale and moisture. Convenient minimum installation time into your compressed air system.