The Barefoot International V Drive Sac 400 Lbs Ballast Bag Set are 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. They are similar in size to the Fat Sac but a bit shorter in length for a perfect fit. Combined with the weight of the engine, these sacs will produce a monster wake. Will also conform to fit in other places and in other types of boats.