1 inch long by about 5/16 " in plastic case roller appears to be steel rolling on a pin. No numbers or name on roller or windows. Windows are original to house built in 1996. Maybe a substitute would work.
Bob from SWISCO responded:
September 16, 2020
The closest match seems to be something like our 87-147, but you'll need to compare all the dimensions to see if this could work for you. Let me know what you find.