Do i need the am2 backplate if i want to install a thermalright 120 extreme on a am2 chip (msi k9n sli)mobo

I am thinking of getting the thermalright 120 extreme so would like to know if it will install out of the box onto my am2 chip on a msi k9n sli mobo without having to buy a seperate backplate? I cant find any site giving a definite answer including the thermalright website.