Protect your mainsail from damaging UV radiation with our top-quality marine acrylic canvas covers. A clever extendable panel, attached to the cover with hook-and-loop tape, lets you extend the cover length up to 2' to cover the end of your boom. We've sized the girth measurement generously so the cover will fit stiff, new sails, and those that weren't flaked properly. Lined to protect against most winch chafe. Zipper closure along the mast, with side release buckles under the boom. Cover lengths shown are overall lengths, from the front of the mast to the end of the boom.