This is a single module of Samsung 16GB DDR4 UDIMM operating at 2666MHz (PC4-21300) with ECC (Error-Correcting Code) capability. It is a Dual Rank (2Rx8) module designed for servers and workstations that support Unbuffered ECC memory.
Field Engineers
Server Fleet Uniformity
"The M391A2K43BB1-CTD is the primary choice for Field Engineers performing critical Server Fleet Uniformity tasks. It meets all OEM performance specifications for Samsung systems."