@orangey03 – I think that the size would depend on your needs. Bigger companies that need a better connection would probably use a bigger antenna.
I've seen silver, white, and black ones. They look like square canvases an inch or two thick. One that I saw looked like a TV screen in a frame.
My office has an outdoor panel antenna that is medium sized and silver. The building down the street has a white one, and my dad has a black one at home.