Stainless Steel hex head plug for O2 bungs. CNC machined from 303 stainless steel. For sealing off O2 bungs when not using an O2 sensor or wideband port. CNC machined from stainless steel ,1-1/8" OD, 3/4" hex with M18 x 1-1/2" threads x 1" overall length. Recommended use of Neversieze when installing.