Corsair XMS3 Dominator ram - is this true?

Hi,

I am about to buy a pc very soon however i got an offer to get corsair for very nice price (around 70eu - 4GB) , but however i never before met this module of corsair
"Corsair 4GB (2x 2GB) DDR3 1600MHz XMS3 Dominator with DHX" - i believed XMS is another class and dominator is another - what is this - dose this ram actually exists and how good it is if it dose? - i could not find any info googeling about it,

thanks!