A professional from Milford Reg. Medical Center says:
January 12, 2016
We are a medical facility and in both of our c-sections room we have built in SS cabinets with doors that work with sliders. The slider bracket works with a roller. The bracket is a Grant Rocket #1012 (1/4" offset and roller is 3/4"). Note the attached pictures. We are looking for 32 replacement units.
Tom from SWISCO responded:
January 13, 2016
This looks like a closet door roller. Perhaps it was retrofit for the purpose you described. Either way, see our 23-009. This appears pretty similar, but see what you think.