This is the same material as Red Silk - Skylight/HDR, it's just faster to render. The reflection is included in the material. It will work even without a decent environment to reflect. However, it will look the same no matter where you put it, so it won't blend into the scene very well unless you use the same environment map as the real environment. It can be a bit more work to keep these in sync, but it's worth it for the speed.