Although fair-weather cyclists may consistently appreciate the ventilation openings in most bike helmets, riders who brave the cold aren't always so keen on them. One solution is to cover those holes using a shower cap-like helmet cover, but Italy's Limar offers an alternative. Its Velov helmet has air flow-blocking panels that can be installed or removed as needed.
The helmet utilizes four panels – one on either side, one on top and one on the back. As can be seen in the video at the bottom of the page, they can all be left installed on cold days (or rainy ones), the two side panels can be removed for limited ventilation when it's a little less frigid, and they can all be taken off on warm days.
Users are able to remove and install the panels by hand, as they reportedly just "click" into place.
The Velov was first introduced last year, although it recently became more widely available in markets such as North America. It weighs 300 grams (10.6 oz) with all the plates on, and is priced at US$105.