Thomas' Timepieces - Seiko 6138-3000 and 6138-3002, both models often referred to as the Seiko Jumbo. The Seiko 6138 was arguably the world's first automatic chronograph (Zenith/Movado El Primo also claimed to
Vintage Seiko 6138-3002 JUMBO Chronograph Automatic Black Dial Works And Stops | eBay
1973 Seiko 6138-3002 "Jumbo" Chronograph
Sold Price: SEIKO Jumbo gents wristwatch with chronograph - December 6, 0122 11:00 AM CET