A non-rigid object holder unit for use in examination of an object, the unit having a base support, a member movably mounted with respect to the base support to accommodate various sized object. One or more gas injection devices, such as porous metal devices, are located in either of the two portions of the mold. The transverse pinning layer of the read sensor is made of an antiferromagnetic Pt\u2014Mn, Ir\u2014Mn or Ir\u2014Mn\u2014Cr film. In another embodiment, the supercritical etching composition includes a supercritical component, which is capable of etching the particular exposed inorganic material. The characteristic shift voltage is higher than the characteristic measuring voltage, and the characteristic measuring voltage is higher than a driving voltage.