VIVO Clamp-on Wooden Mouse Pad Holder Platform, Adjustable Under Desk 360° Rotating Tray Rest Extension Attachment, up to 5cm Desktops, Black, MOUNT-MS01B

Nice flat surface that scoots out of the way when not in use. I mounted the board upside down so that it can act as a stable platform for my VKB Gladiator joystick.I'm giving it four stars for two reasons - there's two thumbscrews that adjust the clamp, one is for attaching to the desk itself, the other is to increase the stiffness of the rotating pad. That second thumbscrew is quite difficult to tighten and requires a strong finger grip. Fine for a younger guy, but I can see some of the negative reviews really struggled with it. It could be a problem if you don't have the grip strength. Other clamping systems I've seen use a lever to clamp which would easier, but might add bulk and cost.Secondly, there is a silicone pad for the top of the clamp that attaches to your desk to stop it moving around or damaging your desk. However, I found this pad has left a very small mark or stain on my solid wood, coated desk. And it doesn't come off with soapy water or isopropyl alcohol. It's not very visible and requires a torch light on it to see, but it there. I recommend cutting a piece of paper or thin card the same shape to prevent this happening. Still grips nicely.Will probably buy another for the left-hand side.