Of the early Heuer chronographs, the first generation 3646 are among the most coveted. Featuring large registers, one characteristic being the 30 minute chronograph counter powered by a Valjoux 92, and a very distinctive dial layout, it is unsurprising the watch has become iconic. The current unknown market example has remained in excellent original condition, with original lume on the hands and indexes, original bezel and clear writing on the caseback indicating little polish.