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Keuffel and Esser Model 4054 "Polyphase"

• Type: Closed Body Enhanced Mannheim
• Size: 10 Inches / 25 cm
• Material: Mahogany and celluloid
• Scales:
  • Front: A [ B CI C ] D K
  • Back: [ S L T ]
• HvH: best match 4145

Black paperboard box. Unit conversions and materials properties on reverse. Serial number 219748

The serial number suggests a date of manufacture around 1945, the cursor and other markings match that date.

This is the second version of the 4054, and is a cheaper model of the 4053, lacking the inch and centimeter scales.