Micrometric fasteners (sometimes called micometric or ratchet fasteners) are probably the most popular way to fasten a modern crash helmet. They’re easy to tighten up and, importantly, very easy to loosen. Just make sure you adjust yours from time to time to ensure it stays a nice and tight fit. See here for more information on micrometric helmet fasteners.
We love micrometric fasteners so we put together these pages – all the helmets below have a micrometric fastener.