i need to add RAM (8GB), can you mentioned what do i have to look for to find suitable RAM for my laptop

[MaGoOoDy]

i need to add RAM (8GB), can you mentioned what do i have to look for to find suitable RAM for this laptop (Dell Inspiron i7559-2512BLK) here in this link (click here)

i need also suggestions for cheaper options

 

[rgd1101]

http://www.crucial.com/usa/en/compatible-upgrade-for/Dell/inspiron-15-(7559)