Hanna portable waterproof dissolved oxygen meter, model HI9142 

HI9142 is a rugged, waterproof meter that solves the common problems of field use, such as cold, rain, snow and dust that can damage a meter, rapidly deteriorating its performance and life.
• Waterproof
• Simple o calibrate
• Built-in thermister for temperaature management
• Polarographic probe with 4 m cable