The media to be measured is transferred to the sensor via a small plastic tube or the pressure sensor needs to be in contact with the media to be measured such as a barometric air pressure sensor, air flow, pitot tube pressure Pressure sensors options include gauge, absolute or ultra low pressure differential pressure reference and usually from 2 inch of water column to a maximum of 300 PSI. The sensing technology used is Piezoresistive or MEMS (micro-electromechanical system) which is effectively a strain gauge whose resistance changes due to pressure variances. Pressure transducers are available with analogue or digital I2C or SPI interfaces.