This weld-in steel bung allows you to change or move your petcock location to wherever you desire. Also very useful for oil tank fittings. 1/4" NPT thread, steel. Sold in 4 packs. Made in Ohio, USA National Pipe Thread (NPT) is a U.S. standard for tapered threads used on threaded pipes and fittings. The taper on NPT threads allows them to form a seal when tightened. These are NOT used for mounting bungs as standard bolts do not fit into the tapered NPT threads.