This piece is the historic Seiko Crown Chronograph (Ref. 5719-8990), famously introduced for the 1964 Tokyo Summer Olympics as Japan's first-ever chronograph watch. Model & Reference: Seiko Crown Chronograph, Ref. 5719-8990 / 45899. Production Date: August 1964 (indicated by serial number ⁠4803134⁠, where ⁠4⁠ stands for 1964 and ⁠8⁠ for August). Movement: Caliber 5719 — a manual-wind, single-pusher (monopusher) mechanical chronograph movement with 21 jewels operating at 18,000 vph. Dial & Hands: Silver sunburst dial signed "SEIKO Chronograph" and "DIASHOCK 21 JEWELS", featuring a tropical patina in the center, applied indices, and dauphine hands. Bezel: Black plastic bidirectional rotating outer bezel used to track elapsed minutes (acting as the minute counter since the watch lacks a separate sub-dial). Case & Case Back: Stainless steel case with a single pusher at 2 o'clock and screw-down case back. The case back features the etched Olympic Flame emblem along with the "WATERPROOF" rating and serial markings. Case Dimensions & Weight Case Diameter: 38 mm (excluding crown) Case Diameter with Crown: ~41 mm Lug-to-Lug Distance: 45 mm Case Thickness: 11.2 mm Lug Width: 18 mm Weight: ~45–50 grams (head only) / ~80–90 grams (with standard stainless steel bracelet)