The Solinst 122 – oil water interface meter provides accurate measurement of product level and thickness in wells and tanks. Determination of both floating no-aqueous liquids (LNAPL) and sinking no-aqueous liquids (DNAPL) is quick and easy. Equipped with state of the art electronics ensuring clear signals at all times and 30 m of narrow flat tape on a convenient small reel. Provides accuracy of 1/100 ft or 1.0mm. A steady tone and light indicate LNAPL or DNAPL. Intermittent signals indicate water.