Have you ever installed a banner with velcro outdoors? What would be the best velcro to use in this situation? Banners will probably be around 50' x 5' with a 2" velcro (loop) sewed around the perimeter. Velcro (hook) will need to adhere to a smooth concrete/brick wall, outdoors, and last 4-6 months. I have seen this done in a couple places before just wasn't sure what the best velcro to use would be and where to get it.