pella sliding door wheel

I'm afraid I don't recognize the part based on this photo. It's very unclear, and it also appears the roller is still installed, so many important details are obscured.

That said it might be a match for our 81-244. This is mostly an educated guess, though. Your next step should be to remove the roller from the door to verify that the details match up with our part.

Alternate image for 81-244