Use this Eight.3 ballast system underneath your seats, in your locker, or on the bow to maximize the wake behind your boat. The trapezoid ballast bag features an anti-roll shape that won't move around your boat while you're out wakeboarding. This simple, fast ballast system includes a telescoping chamber with secure TiZip waterproof zipper. Heavy-duty, 60-gauge tarpaulin material includes high-strength, sonic-welded seams for the utmost in durability. Designed with a 1.5" diameter fill port, plus three 1" diameter external drain/vent ports. 42"L x 18"W x 16"H.