Specific gravity is defined as the ratio of the density of a substance (mass per unit volume) to the density of water or any other reference substance like dry air. The temperature and pressure must be maintained same while measuring specific gravity. By calculating the difference between empty and filled flasks and dividing by an equal volume of water, the specific gravity bottles enable liquid densities to be determined. With strong, clear manufacturing, the containers can accommodate even volatile liquids or semi-solid bitumens. Caps may be provided to prevent evaporation damaging results. Graduated necks promote easy measurements. The specific gravity bottles are available in different capacities and shapes to work with particular materials to give precise measurements.