Abstract: A drill string section for use in making up a drill string for oil and gas drilling carries instrumentation for measurement and logging while drilling. The instrumentation includes a dynamic pressure device for measuring drill string bore pressure of incoming pressurized fluid and drill string annular pressure of returned pressurized fluid. The drill string section comprises a length of drill string pipe having a bore defined by an inner surface of a wall which has an outer surface. The instrumentation is provided in an elongate cylindrical tool shell. The outer surface of the tool shell has spaced apart seals which engage the inside surface of a cylindrical landing sleeve in the pipe bore. The seals are located in the sleeve on either side of communicating port(s) in the drill pipe wall, forming a leak tight annular region that eventually communicates through appropriate ports to a pressure transducer.