Update: This vanity box is shown in a catalog picture on page 241 of the Autenreith book on Co-Operative Flint Glass. The measurements are given as 6 1/2" x 6 3/8".
This compact is listed in the Whitmeyer's "Bedroom and Bathroom Glassware" book as a Fostoria product. Knowledgeable researchers have not found any documentation that Fostoria every made any compacts. Sandy Walker says most researchers have decided that this is a Co-Operative Flint compact.
A Co-operative Flint collector, Harold Bertinarchi, says he has a 1928 ad that pictures the piece. He also said there are slight differences between Fostoria and Co-operative Flint finials. The points on the tails of the Co-op pieces are rounded where Fostoria's have sharper ones. The top center piece on the Co-op piece are slightly diamond shaped where the Fostoria piece will be more oval. Mr Bertanchi has this compact in green.