roller assembly for large mirror sliding door

Hello there!

Thank you for reaching out to us. This appears to be only the inner portion of a complete roller assembly. The outer portion is likely still inside the door. If you can show us photos of a complete roller assembly, as well as the dimensions, we'll do our best to narrow down some options. 

It can be hard to say with certainty but the 23-288 might be what you have. This roller is secured in place using the 33-103 screw mounted at the top of the roller housing through the bottom rail of the door. To access the set screw, it looks like you need to remove the bottom rail off of the door. 

Or if your existing housing is in good working order, look at the 81-228 wheel and the 81-310 axle kit along with the related videos. This might be another way to repair your door.