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The SEE calculator was manufactured by the Selective Educational Equipment Corporation in the U.S.A.   It was a simple circular dial adding machine made  with see-through plastic to illustrate the mechanism.

This type of adder is not infrequently referred to as a "Pascal-type" adder, but the mechanism (see below) benefits from three centuries of development and modern materials to allow a much simpler arrangement than Pascale's to achieve what is essentially the same capability.  Note that like the Pascal calculator the SEE relies on complementary arithmetic to achieve subtraction.

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For patent data see [[http://www.boelters.de/Rechenmaschinen/Zehneruebertrag/ten_carry_pics/dial-pat.gif]] (viewed on 30 Aug 2012).

For comparison, the carry-forward mechanism of the Pascaline (which allows the 1 resulting from 9+1 to be added to the next register to the left) is shown below. 

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