Thank you for the message, and the interesting photos. Here is what I know about the MHT (also known as the "Non-Calculator Calculator"):

• This is Reference 11633 MHT.

• It makes its only appearance in Heuer's 1977 catalog (shown below).

• It's a rare one -- to my recollecton, we have only seen one of these, over the last few years.

• The "MHT" stands for "Minutes / Hours / Tachymeter", because this chronograph has the Minutes and Hours marked on the outer, rotating bezel, and the Tachymeter scale marked on the inner, fixed bezel.

• It's difficult to suggest the value, versus the normal Calculator models. We have only seen one offered for sale; I recall that it sold at a discount to the price of a standard Calculator model; I would think that this discount arose because of some (mistaken) questions about authenticity and some of the weirdness factor -- people probably want their Calculators to be able to calculate.