Today’s drilling operations use steerable drilling tools, which simplify the task and enable access to resources in more remote locations. These tools rely on a combination of three-axis accelerometers, or other position-determining sensors, and magnetic field sensors such as fluxgates. Using low-noise fluxgate sensors in Measurement While Drilling (MWD) tools helps to improve tool accuracy. The high-temperature Mag610 and Mag611 probes, which can operate at up to 175oC and 215oC respectively, provide the lowest noise performance. The Mag614, can operate at up to 175oC, but also offers small package size.