Rollers for sliding, bypass closet doors; doors slide on top-mounted track.

This is a little unusual, as it looks like you need the 23-199 or it's ball-bearing equivalent, the 23-225; however, these rollers typically run along the bottom of the door. It's possible your door was installed upside down, or this was some sort custom job. Either way, these are our closest matches. See what you think.