Don't remember any mention of that or perhaps I just overlooked it. They were just "plug and play" as far as I remember. Do know they seem to work well. Had a newly rebuilt rack made up by TRF installed along with Richard's heavy-duty clamps. All is good. Before the new rack, I snapped the standard U-bolt/aluminum aftermarket clamp. U-bolt popped. Goodparts unit is very high quality, as is everything he sells.