In 1968, Knoll Associates, now the Knoll Group , bought the Gavina factory, which continues to produce the chair. About 250,000 Cesca chairs have been sold since 1968, said David Schutte, a product manager at Knoll.

But Breuer, who worked with both Gavina and Knoll, made some design changes over the years. The curve of the chair's back became shallower and its bentwood frame was two pieces rather than one, for strength; the seat's front edge does not slope as much as it did; the bolts are smaller.

What's left? The hand-caning, the chrome-plated steel caps on the tubing and the rods to sustain the tube shape. Cheaper chairs are based on the Knoll version, not the original 1928 design.

"We spend considerable time and money to get the exact detailing, but these monies are gone when people plagiarize us and change the details," Mr. Magnusson, the Knoll Group official, said.

Sergio Palazzetti, a copyist, said, "Why charge a client for something not paid for?" He offers a machine-caned chair for $312 and a hand-caned chair for $362.

The curve of the metal near the bottom of the chair's back is slightly sharper than that of the Knoll Group's chair. The caps of the tubes are brazed -- the metal is annealed with heat -- and a mandrel is used."It's a quite good reproduction," Mr. Hanks said. Ms. Johnson agreed.

At the Workbench , hundreds of thousands of copies of the Cesca chair have been sold since 1955. "At one point the price was down to $39," said Warren Rubin, the store's founder. The current price is $59. The two visitors noticed that the curve of the Workbench chair's back was shallower than the Knoll Group's chair and the seat extended farther forward. The chair is stiff when it should be springy. The seat rises at the back instead of being parallel to the floor.