Shallow Fill Softside Fluid Beds | 3″ to 4″ Depth: Individual tube placement allows each person to adjust the feel (firm or soft) of their side of the mattress by filling each cylinder with different levels of water so you can create the feel you desire. Shallow Fill Beds overall weight is 50% less than top selling Mid-Fills and 63% less than luxurious Deep-Fills. Also the portability of Cylinder Tubes weighing 40 lbs makes moving extremely convenient!