Standard sailcovers are designed to cover the sail when it is lashed to the boom. Webbings and side release buckles hold the cover closed. A heavy duty zip may close the front of the cover. All sailcovers are manufactured with chafe protection around the mast area.
Stackpack sailcovers are designed to open and allow the sail to be hoisted with the cover acting as a guide ( lazy jack). The cover is attched to the boom using aluminium awning tracks. If your sail is loose- footed, the track on the boom can be used instead. Most stackpacks will have battens to which lazy jacks lines will attach. A heavy duty zip runs the length of the cover. In some cases a small front section will be needed to cover the head of the sail when the stackpack is closed.