As I recall (which may not be accurate as I have fallen out of keeping up with brands until I'm AV-ed) the GSG-5 rebrand that site carries is an Echo 1 / JG or a CYMA . Judging by the metal body and generic picture, I'd say it's a CYMA. However, with the FPS they have listed there, the CYMA theory seems discredited as their guns usually have an FPS of 350 - 450.
Whatever the case, I'm going with everyone else. If you are in the US, don't skimp out. Buy from a more reputable site. Even if you do buy this gun and it turns out to be a CYMA, it's overpriced. This same model, shooting 400 FPS is only $175 on Airsoft GI.
My personal favourite of that site "Full Simi Auto" and "FPS: .12g BB: 365"
What is Full Simi Auto? I know a girl named Simi, that's odd.