16GB ( 1x 16GB Module ) DDR4 2666 MHz ( PC4-21300 ) DDR4 SODIMM ( 260-Pin ) ECC SODIMM ( ECC Unbuffered SO-DIMM ) 1.2V - DDR4 Standard Voltage Compatible Equivalent for Synology D4ECSO-2666-16G, D4ES01-16G Compatible with Synology DS1522+, DS1618+, DS1621+, DS1621xs+, DS1819+, DS1821+, DS2419+, DS2419+II, DS2422+, DS3617xs, DS3617xsII, DS3622xs+, DS723+, DS923+, DVA3219, DVA3221, RS1221+, RS1221RP+, RS820+, RS820RP+, RS822+, RS822RP+ All modules undergo quality assurance testing to ensure dependable and reliable performance Please verify the supported memory (RAM) specifications of your system prior to purchase to ensure compatibility A-Tech provides a Lifetime Warranty for all orders & offers complimentary United States based Tech Support before, during, & after your purchase