This is from a matched set of four, each in a different color of naugahyde. Please see photo below. This set was sold at auction in Los Angeles in 2006; the auction house reported their understanding that these came from a Herman Miller sales representative. The fiberglass shell has a date stamp of 1972; the upholstery tag has a delivery date stamp of 1975. By this time most shells were made without attached shock mounts, they were provided, as this one was, with loose rubber washers that fit between the base and the shell. You can see that in the additional photos below. Also, note another feature of this mid-seventies shell: flattened areas, integral to the shell itself, to receive the bolts. Note the original, Eames Office specified, hexagonal bolts which secure the base to the shell.