Here you can see the other side of the little rubber cap. They slot very easily over the cleat and when you're about to get on the bike, they remove easily and occupy a tiny amount of space in your jersey pocket.
The packaging. Sorry, I couldn't rotate these photos, so you'll have to rubber neck a little. Click them to enlarge.
Exustar do various versions for different cleat types, as per the table below (click to enlarge).
And a little bird on a fencepost, just for the sake of it!