Synology DDR3 RAM Module 4GB (RAM1600DDR3-4GB) DDR3-1600 unbuffered So-DIMM 204pin CL=11 1.5V Applied to Synology DiskStation models: DS2015xs, DS2415+, DS1815+, DS1515+ Applied to Synology RackStation models: RS2416+/RS2416RP+, RS815+/RS815RP+ Also known as Synology RAM Module RAM1600DDR3-4G For expanding your Synology NAS server's memory capacity