The DDR3  RAM is rated at 1.2V and has a latency of CL19. It can operate at a max of 1333 MHz
A memory upgrade should enable you to load programs faster, improve responsiveness of your desktops and offer smooth multitasking and running data-intensive applications.
You will also see great improvements in even simpler, yet important process of working with Web-browsers and spread sheets.
Model :2GB PC3 10600u
Frequency : 1333MHz
240 Pin Unbuffered Dim Dual Channel
Compatible in all Major DDR3 Motherboards (G41 H55 H61 H81)
1×8 : DDR module has to hold 8 physical RAM chips soldered in serial 1 rank  for DDR .

PC3 1Rx8 10600u

DDR3 memory 1.2V (can be double voltage RAM).
1 ranks of memory per module/ stick.
8 physical memory chips in 1 rank on the RAM module.
The speed of DDR3 RAM is 10600 MBps.