Tandem roller

Looks like a pocket door roller. I cannot tell what you have from these photos, but you can see our entire selection of pocket door rollers here.

Keep in mind that these kind of doors aren't as popular as they once were. Most pocket door rollers that come across my desk aren't on the market anymore. In those situations, your only option is to replace your setup with a new track kit, which you can see in the section I linked to above. Sorry we can't give a more confident recommendation!

Take a look at the two images below. These are from older customer discussions, but should give you a better idea of how this roller looks while assembled with that T part.

Hey, Benny. That's great news, thank you! Your business means a lot. As for installation, I've never done it myself but I believe it's straightforward; you'll have to remove the track and slide the roller into it from the end. This can be an issue for some pocket doors where the track is literally built into the wall, but that does not appear to be something you need to worry about. 

Please let us know how it works out or if you run into any issues. I'll do my best to help walk you through it.