These aluminum barrel nuts slide into the ½" (13mm) Keder Rail™ awning track mounted along the top rim of Airstream Basecamp™ trailers and other 1/2" awning rails. Stainless steel eye bolts are held in place with neoprene-backed stainless steel washers, allowing you to securely anchor your MoonShade to either side of your vehicle. (Please note: some of the new 2023 models have some screws in the track that may need to be removed in order to slide the 1/2" Basecamp anchor passed this point. Once the screw has been removed and the anchor is passed the screw hole, simply replace the screw.) Product Specs Materials Stainless steel + aluminum barrel nut. Dimensions- Cylindrical Nut 0.5in diameter by 1in length Ring Bolt 1.625in L Ring bolt inner diameter 0.625in