Buy the all in one units for an I/S if you have a standard or tourer. Cheaper.
I believe the all-in-one dampers for interstate have now superseded the original parts for standard and tourer, which were in two parts (the rubbers and the grommets separate).
If yours are still in good shape and not crumbling, some have shoved strips or rubber inner tube in them to snug them up, but I'd rather have new. Also, make sure to get the cover plate on correctly (upside down is wrong).