Hey '24,
Are you talking about the long "u" shaped pieces like you would put on the edge of a door to protect against chipping? Otherwise, I am not sure what you are looking for. '22
24dodge, This place all kinds of nice reinforced edging that is designed to grip and stay in place when installed. I can't tell if they have any for 18 ga. sheet metal or not. I usually use door edge molding that I get at the auto parts store.
They sell the stuff at most sheet metal supply houses and HVAC supplers. Many types and sizes available, usually less expensive than a specialty suppler.