The 50005 concentric ring probe is an instrument to be used in conjunction with a resistance meter, such as the Desco 19787 digital surface resistance meter, to measure surface resistance per ANSI/ESD STM11.11 the test method listed in packaging standard ANSI/ESD S541 for surface resistance of planar materials. The concentric ring probe (Ref: ANSI/ESD STM11.12) can measure the volume resistance of planar materials using a flat conductive metal plate (not included). Also, may be used for the resistance measurements of ESD packaging including static shielding and other bags.