DDR &ndash; DOS Dual Dosing Reservoir - Neptune Systems Apex Size (Approx.): 10.5 x 8.5 x 5.5 Fluid Capacity (Approx.): 2000ml per side Weight (Approx.): 2 pounds Requires: Apex, Apex Lite, or Apex Jr. and DS to operate sensors Package includes: DDR, 4m of DS tubing