GOLD ROLEX SPEEDKING REF. 6421, CIRCA 1955 Three body tonneau Oyster 9K gold case, n. 80630, reeded bezel with reliefs in correspondence of the hours, concave lugs, screw back stamped 6421, Twinlock crown. Not original strap and buckle.
Silvered dial signed, crown logo at 12, applied arrow indexes and Arabic numerals side by side with tritium dots, minute/second divisions. Luminescent alpha hands, centered seconds. 
Signed manual winding movement, rhodium-plated caliber 1210, n. 87905, 17 jewels, indirect seconds, lever escapement, monometallic balance with screws, blued Breguet hairspring, KIF shock-absorber.
Diameter Ø: 30 mm
Note: working, but a servicing is suggested.