Outer Armor’s™ Vacu-Hold® system is a unique, patented design that enables a covered craft to be trailered at highway speeds… WITH NO HOLD-DOWN STRAPS!! A unique vacuum/vent is incorporated onto the cover. When the covered craft is trailered, a negative pressure is created, keeping the cover tightly in place. There’s no billowing, whipping, or buffeting preventing damage to the craft while prolonging the life of the cover.