An apparatus for use with a wafer prober and a probe card comprising a stiffening member having a feature defining a first plane. The stiffening member is mountable atop the central portion of the probe card. A reference member is provided to mount to the wafer prober and has an underside with a feature defining a second plane. When the feature of the stiffening member defining the first plane is urged against the feature of the reference member defining a second plane the probe tips of the probe card are substantially planarized relative to the wafer prober.