Note the different brands in the picture, they can be mixed and matched. Deal is NOT for all pictured, just showing the brands I have.
Example:The SK Hynix 2GB 1Rx8 PC3-12800U 11-12-A1 HMT325U6EFR8C-PB is a 2GB DDR3 non-ECC unbuffered (UDIMM) desktop RAM module operating at 1600MHz (PC3-12800) with CL11-12-A1 timings and a 1.5V power requirement. Key features include a 1Rx8 rank, 240-pin form factor, and a single DIMM configuration.Key SpecificationsManufacturer: SK Hynix (Hynix)Memory Type: DDR3 SDRAMCapacity: 2GBSpeed: 1600MHz (PC3-12800)Rank: 1Rx8 (Single Rank, 8-bit)Form Factor: DIMMPins: 240-PinECC Type: Non-ECC Unbuffered (UDIMM)Voltage: 1.5VTimings: CL11-12-A1Decoding the Model NumberHMT325: Hynix, 2Gb (gigabit) chip densityU6EFR8C: Hynix internal identifiers for the DRAM modulePB: Part of the module's configuration, often indicating it's for a desktop (PB for "PC/workstation/desktop")PC3-12800U: DDR3 memory running at 1600MHz, with "U" signifying an unbuffered DIMM for desktop systems