Pretty straight forward.  I have two versions for if this goes on a RoStockMAX or SpiderBot.  The RostockMAX setup puts the spools really high but that keeps them lined up with my extruders.  Since the arms are so long they needed fins and that is why there is a left and right version.  Also the RoStockMAX base is attached using small mount holes on each side.The SpiderBot setup uses a different base which has plug to fit in the hole that was used for the OEM horizontal spool holder.  Also it doesn't need such long arms.