cigarette lighter caps?

[wide body]

the previous owner of the truck must not have liked the caps that are usually over the cigarette lighter plugs. is it possible to get new caps? where from? and can i just "pop" the new caps on? the only thing left of the old caps is a "ring" around the lighter. i tried to pull them off gently and they didn't come off, but i was afraid to pull to hard. any ideas?