Electrical TDS Indicators are effectively used in water demonstrations to show the presence of total dissolved solids. The degree of TDS present is shown by the amount of iron oxide produced in the water sample. TDS Indicators can be valuable sales tools by providing a visual comparison between the amount of TDS present in tap water and treated water.Twin 16 oz. water cells allow the user to demonstrate tap and purified water at the same time.Specifications:Size: 4-1/2 x 3-1/2 x 8-1/4Jar Capacity: 32 oz.Weight: 3-1/4 lbs.