1> Seawater Hydrometers 2> Good quality 3> Reasonable Price 4>OEM offered IMPA CODE:651341-44 Seawater Hydrometers Aglass instrument for measuringand staturation of salt in seawater,Aballasted float carrying a scal that indicates density as rated to fresh water, Zero is 1,000;The density of seawater is about 1,026,but varies, in different areas between 1,000 and about 1,040. Seawater Hydrometers