If you use Revit’s Fabrication Parts, CADmep or any of the other Autodesk Fabrication products like ESTmep or CAMduct, you use ITM content. ITM files can be tricky and time consuming to build. If you don’t want to tackle it yourself or just done have time, I recommend Virtual Building Supply (https://itembuilders.com).
There are other companies that will build ITM content for you but their quality varies. Nibco as an example, is two companies removed from the firm that produces their content. As that firm has had some questionable business practices, I won’t get into detail other than to say I can tell just by looking at an ITM if they created it. If they did, I won’t use it.
There’s a few Autrodesk resellers as well who will build ITM content slightly cheaper but don’t put the quality or extra data associated with it into their work.
Virtual Building Supply on the other hand is run and operated by industry insiders. They’ve installed pipe. They’ve managed Autodesk Fabrication databases. They know their stuff.
If you browse to their downloads page, the have a few things you might be interested in…