Accessory rings are present on the FS-78 guide scope and the finder scopes. The three-point pins have had the stock Losmandy delrin pins replaced with stainless steel inserts.  When locking down the original delrin pins to the guidescope, things always felt a bit mushy.  When you lock the steel three point pins/rings down to the accessory rings they hit home and you can literally feel the difference. Solid as a rock.  See all that stuff in the pic below?  It's heavy.  I once accidentally lifted it with two hands with my right hand hanging on to the guide scope.  All that weight was born by the accessory rings and the six pins.  Didn't even budge and nothing bent or broke.  I was astounded (and scared too <g>).  I never tried that again.