Kingston's server-branded DDR4 RDIMMs are built to the registered spec that data-centre and workstation boards expect: an onboard register chip buffers the address and command signals before they reach the DRAM, which is what lets a board run far more memory per channel than a standard UDIMM allows.
Rated 3200 MT/s CL22, this kit is 1×64GB — a single-module 64GB part rather than a kit split across two or four sticks, which is typical for RDIMM in server contexts where slots are populated individually rather than as matched pairs.
RDIMM only works in boards and CPUs whose memory controller explicitly supports registered ECC memory — plugging it into a standard consumer desktop board will not work even though the pin count often looks similar. All memory in this family is ECC, correcting single-bit errors in hardware.