RO PRO tanks are for undersink installations of reverse osmosis systems. These NSF Certified tanks are slimmer and taller than the standard metal storage tanks. SpecificationsDimensions: Width: 9 in Height: 21.0 inDepth: 9 inWeight: 7.10 lbsColor: WhiteSize: 4 GallonsCapacity: 3.2 Gallons*Alternate Part # : FRO-132