This is the rubber "welting" that is installed between two metal products (ie: Rockers to the body or tube fenders to corners).
It is idea to keep the two painted surfaces from rubbing together OR hide uneven surface gaps.
It has a nice round bead at the top, as pictured.
(2) 6 Foot long strips of 1-1/2 Inch tall rubber gasket, welting.
Be sure to click on "More Pictures" to see more detailed product pictures.