It came separate from the chair, but it's on the DX Racer site I love it.
Also, I LOVE my DX Racer chair. REALLY love. I have a crap ton of things wrong with my body, neurological disease, 3 herniated discs, 3 bulging discs, 2 torn discs all in my lower spine. I was crippled after tearing another one a few weeks ago.. Instead of continuing to lay in bed all day with my PC next to it, I opted to get an ergonomic chair instead. I did a ton of research, the DX Racer sounded good. Got one of the R-Series and man.. am I happy with this decision. My back pain went away so quick. This thing is so customizable, I love the mousepad armrest accessory.
Your setup is looking very nice. Glad you found a chair that works for you.