Roller door assembly

I need a replacement roller assembly for an 8 slider door. My existing roller bearings are worn out which makes the door hard to open
The only information I have is on the part: Delmar hardware Toronto
Please see attached photo of the roller assembly.
Note: there are two roller assemblies on my 8' slider.
Please send two roller assemblies so I may have a new
pair of roller assemblies that will wear equally

81-138 does look like a match. Your wheels look small. 1" or 1-1/8". Is there a reason for small rollers? Bigger is better, but not if they don't fit. I've never felt good about tiny wheels.