The hobbyist can take a water sample at six inches in depth without submerging their hands in the water, thus avoiding the possibility of contamination. Samples taken at six inches in depth have been proven to give a more accurate salinity reading than surface samples. Every unit is calibrated and tested for accuracy using advanced testing procedures. With its durable construction and easy-to-read scales, the deep six is guaranteed to provide years of reliable performance. Designed to give temperature corrected readings in warm water aquariums, readings can be read in ppt and specific gravity. The deep six is accurate to +/- 0.001 specific gravity.