Mainsail packs (also known as Stack Packs, Lazy Bags, U Stacks and Mack Packs) are commonly used on boats that employ the lazy jack method of sail handling. The sail may be stowed away in a backpack by simply dropping it in and zipping it up. A lazy jack system (not included) can be used in conjunction with the mainsail pack cover to help steady the top of the sail pack and tuck the sail away neatly. Prices start at $90/foot