Brass Pipe Fitting, Hex Counter Sunk Plug, 1/8 Inch NPT Male Pipe, 10 Pack It is commonly used to seal holes in machinery, fittings or pipes to prevent leakage of air, steam, gases, water, oil, and fluids under pressure. These plugs are also great for blocking off intake manifold water ports, water pump ports, water temp and oil sender holes, engine block holes, etc. Internal Hex applicable for 3/16 Inch Wrench Specification. Material: brass. Groove: Internal Hex. Quantity: 10pcs. Size: 1/8 inch. Note: This product can expose you to chemicals including lead(1.8%~3.7%), which is not allowed by federal law to be installed for potable water use in the U.S.A. and its territories.