When you're in the depths of winter, the Optimus cap is the perfect under helmet accessoryShaped to work underneath a helmet with minimal seam irritationThe windproof fabric keeps the chill off, and the fabric membrane is waterproof preventing you soaking through in wet conditionsPeaked brim keeps the sun or rain away from your faceFold up rear panel allows you to expose the ears if you begin to overheatLimited lifetime warranty