The laptop is the Intel Core i3 version so it has 2 memory slots,
the existing single RAM module is a SAMSUNG DDR3(L) 4GB 1Rx8 PC3L-12800S 1600MHz 1.35V, part number: M471B5173DB0-YK0.
Normally, I would not buy 2 new modules, only one to upgrade the existing one but if you say the existing one...