There is a plastic lid BUT under that is a very thin, Peel off, patterned metal disc seal.
It can be cut to shape with scissors and is just right for treadplate's and because the metal is so soft you can easily tap in your own pattern if the existing one does not suit,
The tub when empty is very useful for storage of nuts and screws or whatever as it comes as I already mentioned with a plastic lid,
I reckon this is a win win.

In fact the only drawback is trying to find someone who will drink the brown muck.

Shaun.