From Wiki

A. W. Faber Castell Novo Biplex 2/83N

• Type: Duplex Log Log
• Size: 15.0 / 9-7/8 Inches = 39.1 / 25.0 cm
• Material: Plastic, metal end brackets
• Scales:
  • Front: T₁ T₂ K A DF [ CF B CIF CI C ] D DI S ST P
  • Back: LL₀₃ LL₀₂ LL₀₁ LL₀₀ W₂ [ W₂' L CI C W₁' ] W₁ D/LL₀ LL₁ LL₂ LL₃
• Date of Manufacture: September 1973 (approximate)
• HvH: variant of 929

As cool as the Novo-Duplex 2/83 was, users thought they were missing something. So Faber added A and B scales (I'm sure they thought they were redundant in light of the W scales) and they added CI and D scales on the reverse for a little flexibility. Also added were LL₀ and LL₀₀ scales. The LL₀ scale is combined with the D scale since e^x approximates 1 + x in the LL₀ range of 0.001 to 0.01. (As the two values diverge, see correction digits marked on the scale for lawyers and other users uptight about accuracy.)

At 30 (or 31) scales, this was Faber's ultimate sliderule; the scientific electronic calculator came out just before these were produced and the slide rule was dead by 1975.

With box, green leather case and celluloid insert with inch and centimeter scales, and metal properties and reference formula, in Spanish. Manual in Spanish. (Obtained from a seller in Venezuela.) The name "Novo-Biplex" was used only in Spanish-speaking markets; there is no other difference from the "Novo-Duplex"