• These roof racks cannot be used with awnings.  Some people have modified their awning, by spacing it out, and have been able use these roof racks.  See this web page.
  
• These roof rack bars need to be 'fitted' to your pop top.  There is some small variation between pop tops of different vans, every pop top is slightly different in width.
  
• The newer bulb style pop top seals cause the pop top to be a little wider than the original pop top seals. 
• To fit these roof racks to your van, you may need to bend the rack bars or the rack feet.  A bench vise is needed. 
  
• You should mount the roof rack bar in front of or behind the roof vent.  You want to be able to fully open your roof vent.
  

• A front bar and a rear bar. 
• Most applications will use two front bars.  The rear bar is only used with a Safari basket.
  
• "Front" and "Rear" are stamped into the metal on the backside of the rack feet.
• The rear bar only fits at the very back of the pop top. 
• On the rear bar, there is a left side and right side, stamped L and R.

Further instructions here