Sunlight is a furling headsail’s worst enemy since the sail lives on the headstay all season. Most cruising sailors protect their sails from the sun with covers sewn on leech and foot made out of UV resistant material such as Sunbrella or WeatherMaxx. However, these covers add a lot of weight to the leech of the sail, which makes the sail sag instead of fly well in light air.
An alternative is the UK Sailmakers genoa sock, which is separate from the sail and goes up over the rolled sail at the end of the day. The sock gets raised on a separate halyard and it is zipped around the sail as it is raised. Once it is up all the way, the lacing lines are cinched so that the sock fits snuggly around the furled genoa.
The Jib Sock is made out of the same UV-resistant materials as used for mainsail covers and biminis, so you’ll be able to match the boat’s other protective covers.
An extra advantage is that if you buy a new sail that you don't need a new sock.