RAM upgrade on Dell OptiPlex 755/USFF (the smallest)

hi i have a Dell OptiPlex 755/USFF, and i wanna upgrade the ram., whats the max i can go and what are the specs ? 

i have

Hynix 4GB DDR2 667 MHz PC2-5300F ECC 2Rx4 CL5 1.8V - HYMP151F72CP4N3-Y5

can i install this?