I would like to buy a longer data cable for my u-verse internet

Hi,

I want buy a longer data cable for my U-Verse Router (Pace brand, 5031NV model. I got it today).

I would like to make sure that I but the right cable. It is the one that plugs into the green outlet on the router, and the green outlet on the filter (the filter being the thing that plugs directly into the wall).

So my question is: what are the specifications of this data cable? In other words, what should I look for on e-Bay or Amazon?