Tri-axial sensor probes have three mutually perpendicular sensors, consisting of fiber films. The sensors form an orthogonal system with an acceptance cone of 70.4°. Used for measurement of the U, V and W velocity components in an instationary three-dimensional flow field. Provides information for calculation of the full Reynolds shear stress tensor. Mounts with the probe axis in the main flow direction. The resulting velocity vector must be within the acceptance cone.