Dial-a-Metric

A system of units conversion device which includes:

• three coaxial circular discs, two outside discs and an inside disc, mounted for relative rotation about their common axis;
• the inside disc having sets of contiguous juxtapose circular scales arranged at least one radius with numerical indicia linearly related to their angular displacement about the common axis of said discs, such scales being on both faces of said inside disc and each set having a different identifying color background,
• each scale having the value of said numerical indicia also linearly related to a physical quantity, as described by a system of units;
• the scales of each set being for the same physical quantity;
• the outside discs each having a die cut window for each physcial quantity angularly separated about said common axis and at such radii to uncover at least one set of said scales per window and said windows having indicia with background color matching the corresponding said identifying color background of the sets of scales to clearly match said physical quantities of said windows to said scales, particularly where a plurality of windows have the same radius;
• a hairline contiguous with each window;
• wherein each set has at least one scale in one system of units and at least one other scale in another system of units whereby the conversion from said one system of units to the other system of units is facilitated.