These are cozy ear-warmers worn over your helmet straps, secured with velcro inside.
Some local cyclists might remember "Earwigs", which are very similar but haven't been produced for years now. You can't find anything like these locally (except for the Fairfield Bicycle Shop, now) or even on Amazon.
Mine have a few improvements over the Earwig design: the velcro is positioned lower down so that they don't slide down the straps. The top is curved, to ensure the ears are fully covered. They come in variety of colours and patterns, are reversible and there is a kid’s size.
The packaging is repurposed from bike helmet boxes, and if turned it at time of purchase gives you 25¢ off the price. Only $14.99! (or $14.74 without packaging).