Model: Oyster Monoblocco Reference: 4500 Date: Circa 1946 Movement: 17-jewel manual wind, Glucydor balance, column wheel chronograph Dial: Silvered, luminous filled alternating Arabic and dart hour markers, black inner 1/5th second divisions with Arabic numeral 5 minute markers, blue outer telemeter scale, black outer tachymeter scale, subsidiary dials at 3 and 9 for seconds and minute recording, blued steel pointed baton hands with luminous inserts, centre chronograph hand Case: Brushed and polished round, screw down back, screw down Oyster crown flanked by twin pushers, No.497400 Strap/Bracelet: Brown associated alligator leather Buckle/Clasp: Associated steel buckle Signed: Case, dial & movement Size: 35mm 注脚 Rolex produced only a limited handful of Oyster chronographs featuring just a 30 minute register as opposed to including a 12 hour register as well. First introduced in the 1940s, the reference 4500 is one of these rare chronographs and was available to purchase in 4 materials - yellow gold, rose gold, steel and steel and gold.