Professional model for taking exact water samples from a desired depth.
Functional principle:
Lower the specimen sampler to the desired depth. Water flows through both spherical valves. When the correct depth is reached, jerk he sampler upwards two or three times to let in the water you want and then pull the sampler up. Spherical valve technology ensures that no foreign water can enter the sampler. To fill Winkler oxygen bottles, a ball value is mounted on the unit which enables you to fill the water into the bottles using he tube (included) without intrusion of foreign oxygen.