Fly High Pro X Series V-Drive Fat Sac Ballast Bags (set) 2011 - The Fly High Pro X Series V-Drive Fat Sac is exactly what you think; designed to fit in the compartments on either side of the engine in v-drive boats, these sacs are perfect for the ballast you need. Similar in size to the Fly High Pro X Series Fat Sac Ballast Bags, but a bit shorter in length for a perfect fit. Combined with the weight of the engine, the Fly High Pro X Series Fat Sac Ballast Bags will produce a monster wake. They will also conform to fit in other places and in other types of boats.