Vmod instructions

Use virtual devices in Chrome's Device Mode to build mobile-first websites. Read here what the VMOD file is, and what application you need to open or convert it. What is the .vmod file? Which program can create the .vmod file? i have this card Powercolor 4870 PCS+ 512mb , i think is rev 2. I can do without any volt mod, 860-1000 for benchs and games, but i think this card can be pencil