"They are made of high density
rubber/foam material which is also used on shoe soles such as the
old Hush Puppies. It has turned out that this material lasts very
well, particularly since the metal 'shoe' takes most of the
scraping. I have had mine on my ASW-24 for about 4 years and they
still look really good.
Ideally, for installation the top
(straight) surface should be sanded a bit to make a slight concave
surface to match the wing contour. It is easy to do with a drum
sanding tool or file, and you can then customize it to fit your
airfoil.
I recommend the use of high quality
gasket silicone material (readily available at all automotive supply
stores) for attaching them to the wing. This provides excellent
adhesion."
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