Rolex

• cal. 72B, manual winding nickel-finished lever movement, mono-metallic compensation balance, 17 jewels • silvered sunburst dial, applied baton numerals with luminescent accent, luminescent hand, three engine-turned subsidiary dials for constant seconds, 30-minute and 12-hour registers, outer minute and 1/5 seconds divisions, outer tachymeter scale • stainless steel brushed and polished case, screw-down crown and back, two round chronograph buttons to the band • case, dial and movement signed • with a stainless steel Oyster bracelet

Introduced in the beginning of the 1960's and available until 1967, the reference 6238 is today known as the "Pre-Daytona". It is regarded as the bridge between the early chronographs of the 1930s-1950s and the vintage Cosmograph Daytonas.
As the majority of the earlier Rolex chronographs, the 'Pre-Daytona' featured a tachometer scale to its dial. With the launch of its successor, the 'Daytona' Ref. 6239, the tachometer was removed from the dial and placed onto the bezel. The new Daytona models were also fitted with dials incorporating a standard base color with differently colored subsidiary dials; the 'Pre-Daytona' was fitted with a single tone silvered or black dial and a smooth bezel.

The present watch was consigned by its original and only owner who carefully cherished it for more than 50 years. It represents a rare opportunity to acquire a piece fresh to the market and in excellent condition. The watch is further distinguished by its beautiful and wonderfully preserved dial. 

For extensive discussion and illustrations regarding Ref. 6238, the 'Pre-Daytona,' see Pergola, C., Mazzariol, S., and Dosso, G., Rolex Daytona: A Legend is Born, pp. 5-42.
Also see Papaleo, P., I Cronografi Rolex: La Leggenda, pp. 278-289.