Heuer Calculator is a real tool watch, the large bezel is not just there for looks, but acts as a slide rule for calculations. This is the largest of the vintage Heuer watches, measured 45mm. This Heuer Calculator Ref. 110.633 is powered by Heuer’s own automatic Calibre 12 . This is an hugely impressive watch, offering enough “vintage” to clearly not be a modern watch, but at the same time having a contemporary size, sitting at 45mm. The Calculator is one of Heuer’s lesser-known Chronographs. The condition are overall mint , it comes with the original s/s bracelet, instruction booklet and blank warranty.