In the measurement of parameters such as temperature and humidity or the like of a high velocity fluid, errors attributed to the velocity are encountered. The device of the invention protects sensors from direct impingment by such high velocity fluid by providing a housing (14) having a leading portion (16) and a trailing portion (14) forming the elongated longitudinal housing (11) with a bore (18) extending longitudinally through the portions for flow therethrough. The flow rate is internally regulated to a desired rate by a restriction (60) in the bore located in the trailing portion. Where the fluid stream is air, the restriction provides for internal Mach number regulation at various flow rates. A first plurality of ports (22) is located in the leading portion for boundary layer control. The device has one or more annular fluid passageways (24) downstream of the first ports coupled to the bore and ported to the exterior to cooperated with the bore to provide a lower pressure area for flow therethrough, and a sensor (38) disposed in at least one such passageway. The leading portion may incorporate anti-icing for air stream measurement. For temperature sensors, radiation shielding (50) is provided.