Density Hydrometer 1.700-1.800 x 0.002g/ml +/- 0.002 @ 20°C approx 250mm long ISO649, BS718. (with certificate of conformity) Made in France by Alla. Accurate density hydrometers, within our approved hydrometer range. Available Australia-wide. Density is the basic unit of hydrometry. Density hydrometers read mass by the unit of volume at a given temperature. For example, a reading of 1200 on an Australian Standard density hydrometer indicates that the liquid has a mass of 1200kg per cubic meter at 20ºC. Find the precise density of a liquid with our high-quality, scientific glassware.*Hydrometer lengths vary considerably for many reasons. Note that lengths in descriptions are maximum/approximate lengths. If length is critical please contact us for exact measurements.