This instrument is combination of pro20 and pro30 instrument.
Its features are:-
1) Internal barometer for highest accuracy.
2) Available with 1, 4, 10, 20, or 30-meter cables (4-meter and longer              cables include cable management kit)
3) Quick Cal allows DO calibrations within seconds with the push of a              button.
4) Choose field DO sensors (Polarographic or Galvanic)