| a screen or mat covered with a dark material for shielding a camera lens from excess light or glare. |
| an extraordinary or unusual thing, person, or event; an exceptional example or instance. |
dime a dozen
So plentiful as to be valueless. For example, Don't bother to buy one of these
they're a dime a dozen. The dime was declared the American ten-cent coin in 1786 by the Continental Congress. [First half of 1900s]