[CR]Who Made These Rollers?

I think these are from the 70s (?):

Description: Folding type; rollers hang down from rails-top of rollers level with rails; rollers are a light blue-robin color; stamped on one of the legs is "R?SGDG" (the ? is a symbol, or over strike, so I can't tell exactly what it is).

Angel Garcia
Long Valley, NJ