Made in Acrylic so the sail can breath. Covers the mainsail when lowered on the mast. Zipper down the front of the mast with snap over flap to protect the zipper. Runs out to the end of the boom and twistlocks around the end of boom. Under side of cover fastens with snaps and twistlocks. Adding your boat name with a monogram really enhances your boats appearance at the dock.