R&R of a Fuel Pressure Regulator
 

I did a search but, no details of doing this. How do I remove a FPR off my '92 400E? I took off the hose the steel braided hose leadking to the FPR but, have no idea how to take off the ring that is holding down the FPR. . It is round ring with two holes on either end and does not a make a complete circle. It has a opening. I tried everything to take it off but, for the life of me. Cannot take it off. Is there a special tool for this? Also, once off, do I just pull the FPR off and install new one?