FATSAC Tube Fat Sac Ballast Bag - 370lbs - Red [W704-RED]Tube Fat Sac Ballast Bag 370lbs Red Thanks to its long and narrow shape, the FatSac Tube Sac is perfect for adding 370lbs of hidden ballast. The FatSac Tube Sac is the perfect shape for ski locker found in the floor of most boat. It's longer and narrow profile also make it incredibly versatile for use in other areas of the boat, such as the bow walk way, or in storage compartments and under seats. There's a reason this is one of our most popular bags;