First Hardin Type Resonant Column With GDS' first Hardin type Resonant Column heading to Australia this month followed by another bound for the USA, the Hardin type cells are proving popular with our customers. Having sold over fifty of the Stokoe cell types, these are the first hardin type systems to be sold by GDS. The Hardin type Resonant Column apparatus (H-RCA) is a system that allows samples to be tested in resonance while maintaining an anisotropic loading. This is achieved by a slender, thin walled loading column passing through the drive system to the topcap. Read More.