Crucial 4 GB DDR3 1600 MT/s (PC3-12800…

8 gig as in description or 4?

It’s 8GB. Updated the title. Sorry about that.

Why limit is 3?
So i can put 4 in my laptop but this limit…

And 4 it is. Buy ALL [4] of the memory sticks.

great thanks!

It works just for mac or is it compatible with another OS or brands?

Is it compatible for desktop. I want to buy it.

You’d need to look up the information on your desktop to see if it’s compatible.

Note that this is for a Mac.