By The Foot for Different Gauge Metals
Using the correct U channel rubber trim extrusion is very important in order to get the best seal. Most important is the edge trim opening it should be as close as you can get to the thickness of the metal you are trying to seal. Next thing of importance is choosing a U Channel rubber with a rounded back or flat back. If you are using the edge trim to seal up against another metal like a tail light seal to protect your paint consider a flat back rubber edge trim seal. If you are using it to cover up a edge for safety purposes like a car door edge and appearance is important probably a round rubber edge trim extrusion would be preferable. If appearance is not important the only thing you should consider is the round back rubber edge trim goes around a corner better than a flat back flexible U channel edge trim.
22 Gauge metal requires a rubber edge trim 1/32 inch opening
16 Gauge metal requires a 1/16 inch opening
11 Gauge metal requires a 1/8 inch opening
7 Gauge metal requires a 3/32 inch opening
3 Gauge metal requires a 1/64 inch opening