You offer two types of pressure gauges – how do I choose one over the other?

RBR standard instruments with a "D" in the name, such as RBRcoda³ D,  RBRsolo³  T.D, or  RBRconcerto³ C.T.D.ODO.Tu,  use piezoresistive pressure (depth) sensors.   Electrical resistance of such a sensor changes when pressure is applied. The sensor consists of a measuring cell immersed in oil and covered by a flexible diaphragm. Any pressure applied to the diaphragm is transferred through the oil to the measuring cell. A clear plastic cover protects the diaphragm from deformation. Ensure the cover is in place and avoid touching the sensor.

The piezoresistive pressure sensor has initial accuracy of ±0.05% full scale and is recommended for most applications. 

The RBRquartz³ family of instruments uses the Paroscientific Digiquartz® pressure sensor for best-in-class initial accuracy and low drift performance. Its operation principle is based on a precision quartz crystal resonator whose frequency of oscillation varies with pressure-induced stress. The resonant frequency outputs are maintained and detected with oscillator electronics similar to those used in precision clocks and counters. See Paroscientific: Resonant Quartz Crystal Technology for more details.

The quartz sensor has exceptionally high stability and initial accuracy of ±0.01% full scale, which come at a much higher price. For example, RBRquartz³ Q | plus is almost ten times more expensive than RBRvirtuoso³ D | wave16.  

The RBRquartz³ instruments are recommended for long-term specialised applications, where their high resolution for sensing small changes in water level is crucial.