This V-Style high flow coupler and plug combination air fitting kit include: (1) Steel 1/4-in MNPT Plug (1) Brass 1/4-in FNPT Coupler Milton's V-Style high flow couplers and plugs are ideal for high volume, low-pressure applications. These couplers will also accept M-Style and A-Style plugs. However, V-Style plugs are recommended to retain maximum flow. With their push-type sleeve release: Simply push the plug into the coupler to engage; Pull the sleeve release back to remove. Maximum inlet working pressure of 300 PSI - 1/4-in basic flow size. Airflow of up to 74 SCFM. We highly recommend steel plugs for use with any type of percussion tool (such as: impact tools, air grinders, polishers, drills, etc.). The use of brass plugs with these tools with cause damage and premature wear to the couplers and plugs.