Hello, up for sale is very rare antique ca.1950's a very rare Bulgarian produced circular slide rule. Special rule produced in Experimental workshop ''ERA'' (for secret and military equipment). The slide rule complexity made of celluloid with double side rotating discs. One side with perpetual calendar starting from 1958 and ending to 1979 an on other side Bulgarian country map on disc with perforation on main cities and distance km calculator. There is an arrow pointer on disc for calculation, when you point at one town name described on border you can seal see the distant to anyone of other marked towns. It is marked with factory mark on bout sides with winged star workshop logo. Very good preserved with minor traces of use. Must have any slide rule collection.

Condition: original as is on photos, Please, be sure to view all photos  carefully as they are included as part of the item description.

  

Measures: 4'' diameter.

Check my other auctions for wonderful antiques and collectibles!

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Auction terms and conditions.

All my items are as described, all authentic and original collectable items. They are described the best way I can. All questions will be answered on time depending on the time-zone differences.

I ship only registered airmail worldwide with tracking number provided.

Package will be securely wrapped to prevent any damage. If needed in double box.

100% refund guaranteed. Do not worry to contact me if you need assistance in any situation. Will do my best to satisfy my customers. Will combine shipping for multiple purchases.

Happy bidding!