I recently received an order for Uart 400 grit sanded pastel paper. I hadn't used this for several years, so was anxious to give it a try. I used an underpainting of dark blue hard pastel dissolved with mineral spirits. I am disappointed in the photo, as it is hard to see the nuances of color. There are many lovely plums which do not seem to show up on my screen. I did like how the paper felt with the pastels.
Edited - one of my online friends helped correct my photo, so below is the better photo.
Pine at the Reservoir, 7.5 x 18, pastel on Uart 400 grit paper