This keyboard tray can move up and down, so you can use any desk it fits on as a standing desk, or adjust it down for sitting and/or ergonomics (the only issue with fit is the length of the track, and whether your desk is deep enough to mount that). I got it new and used it for only a couple months before I realized I needed to replace the very old desk I had put it on. In great shape, and I have all the hardware. These sell for $170 new, it's a solid, well-made product.
Here it is on the company website: https://www.mount-it.com/products/mount-it-adjustable-under-desk-keyboard-and-mouse-drawer-platform-with-ergonomic-wrist-rest-pad-mi-7139