If there was anyone that has perfected the nippy covers, it's OBC. From the reusable adhesive silicons to disposable fabric covers, there are none that's work as amazingly well for me as the 'Mighty Reusable Nipple Covers'.
Those disposal ones? Forget it. They can't keep your sisters from peeking out when it gets draughty. The adhesive silicon ones, sure it works well, until you drop them by accident (sometimes onto the floor) and can't remove the dirt and grim from the adhesive, and when you wash it, it somehow loses its stickiness.
I have been using these babies for more than a year or so, and they still stick well, too well, and too comfortable (I might add) that in fact I still forget to take them off when I go and shower.
It's easy to wash, dry and (re)use them (almost immediately too!) It's compact and travel friendly and my absolute go to whenever I need nip coverage for bralette-less outfit.