Hanna Instruments Anionic Surfactants Portable Photometer with CAL Check Kit

Advanced LED optical system
Innovative optical design that utilizes a reference detector and focusing lens to eliminate errors from changes in the light source and from imperfections in the glass cuvette.
LEDs have a much higher luminous efficiency, providing more light while using less power. They also produce little heat, which could otherwise affect electronic stability.
CAL Check
Validate instrument performance at any time using CAL Check cuvettes made with NIST traceable standards. The CAL Check screen guides the user step-by-step through the validation process and user calibration.
On-screen tutorial mode with animations
Guides users step-by-step through the measurement process
Waterproof and floating IP67 case
Unit of measure is displayed along with reading
Built-in timer
Built-in reaction timer that ensures consistency between tests.
Error messages on displayAlerts to problems including no cap, high zero, and standard too low
GLP data
Displays the last calibration date
Auto logging
Battery status indicator
Auto-shut off