I am a huge fan of Vertagear chairs and will be for a while. One thing I felt this chair was missing was a better lumbar pillow and implementation of the lumbar support. I feel like with the SL specifically, having a knob to adjust a build in lumbar support system would be much better. I just felt like the pillow was way too big and it would be nice to pick the right adjustment for me. Other than that though, incredible chair! I can literally sit in it all day, and have on several occasions without feeling sore.