Basically is the integral orifice is the same of the "meter run"; it is designed according to ASME MFC14M; its dimension ranges from ½" to 1.1/2" and the process connection may be Flanged (ASME B16.5) or BW type (ASME B16.25).
Process instrument will be designed with oval flange DIN 19213 and it is necessary to allow the direct mounting to the DP Transmitter.

Material construction will be the same as piping requirements.