Hmmmmmmmm, someone from F'burg, Spotsy here.
The lens can be clear w/ a amber bulb or a amber lens and a clear bulb.
The lights are required to have a DOT stamp on them, hence there is a size requirement according to DOT.
Those are the official words from the VA State Police Inspection Book.
That doesn't mean you can't put on a Mickey Mouse light and get some fly by night inspector to pass it. BUT if you get in an accident and it is determined that you were running illegal lights and they were not visable by the other driver........the inspector looses his license, the shop will get sued and you my friend are liable for the accident. Hope you have good insurance