The HI96822 is a rugged, portable digital refractometer designed for the measurement of salinity of natural or artificial seawater. The HI96822 displays results in three popular measurement units: Practical Salinity Units (PSU), salinity in parts per thousands (ppt) and specific gravity (S.G. (20/20)). The instrument’s high accuracy and simple operation gives reliable results each and every time. All readings are automatically compensated for temperature variations and displayed with a 1.5 second response time. The sealed flint glass prism and stainless steel well are easy to clean. Just wipe with a soft cloth in preparation for the next sample.