KL-1 (КЛ-1) - Slide rule - Circular slide rule

KL-1 (КЛ-1) circular slide rule, an iconic Soviet calculating instrument produced since the 1960s.

It resembles a classic pocket watch or stopwatch.

Key Features: Purpose:

Analog engineering calculator used for multiplication, division, squaring, and calculating trigonometric and logarithmic functions.

Design: It has a housing with two knobs (crowns) to control the inner dial and two hands (a black, movable one and a red, stationary one).

Reversibility: The device is double-sided. The side shown in the photo contains basic scales (multiplication/division, squares), while the other side is typically used for trigonometric calculations (sines, tangents).

Manufacturer: Made in the USSR; the dial features a stylized manufacturer's logo, stylized as "МАТЕМА" or a reference to precision factories.

Condition: New, never used, in original box with instructions.

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