This cap pushes inside the intercooler pipe when you have the intake elbow off so you can keep debris out of the pipe. It is a super snug fit so you don't need to do anything other than push it in and it wont accidentally come out if you are working in the engine bay. This will fit any 3" intercooler pipe connection which is every 5.9 Cummins from 1994 to 2007.
Current pics of plug installed are on a 6.7 but its the same principle.
