If you are trying to convert to an external crankcse breather setup, see here.
This mini filter can be used if a Rottweiler Intake System is being installed and the user would like to retain the stock emissions system intact. Install this small filter where the SAS valve used to draw air from the stock air-box. (The stock airbox is removed with the installation of a Rottweiler Intake System and the SAS valve will need a new filtered point to draw air from)
Or - this small filter has a 5/8 diameter and can be used for whatever else you need it for.