I purchased 2 of these sets to help supplement and adjust my current work out routine.  I've currently own a Marcy weight cage that has a dual pulley  system in the rear with attachments centered high and low.  My weight bench is a standard Marcy bench that does not allow for the attachment of a leg developer.  Prior to purchasing this set, I could do single arm flyes from the high position in various formats.  This is an acceptable way to accomplish this exercise if and only if you maintain even counts, form, and weight to avoid lop sided development.  This is a lot harder than it sounds.