A landlord from Sicklerville, NJ says:
February 16, 2016
We are looking for replacement rollers for aluminum sliders as pictured. We need the 3 different types of rollers.
Paul from SWISCO responded:
February 17, 2016
I would recommend looking at our 87-003 for the upper left roller in your photo and the 87-016 for the two on the right side. The bottom left roller came from Keller industries, who have been out of business for some time now. The mold of the roller has been lost. Our 87-138 is a possible substitute, but I can't be sure. Please compare its dimensions to your part and see how they match.