The Pro X Series V-Drive Sacs are exactly what you think they 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 our 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.