Power Wheels Magazine A Notch Above
Thank you for logging in to your Power Wheels Magazine and for your interest in our new Timepieces section. To launch this new section, we shall be featuring a different Seiko wristwatch from our own collection each and every day of the month of September.
Today, the 2nd day of September, 2026, we take a look at a Seikomatic Slimdate automatic dress watch (Reference No. 841990) from August 1964. This vintage wristwatch represents a pivotal moment in Seiko’s pursuit of ultra-thin, high-end mechanical engineering. Powered by the thin Caliber 840 30-jewel self-winding movement, the Slimdate is equipped with DiaShock, Seiko’s exclusive shock-protection system, to protect the wristwatch’s balance staff from impacts.
During its introduction, the Slimdate was designed as a sophisticated mid-to-upper tier dress watch for executives and office professionals. Designed to slide easily under a dress shirt cuff, its svelte and slim stainless steel case measures 36 mm in diameter and just around 10 mm thick.
The lug-to-lug length is just under 41 mm to easily fit slim wrists while it weighs only 30 grams to make it light and easy to wear every day. A recessed crown is tucked away near the 4 o’clock position to further emphasize the Seikomatic self-winding/automatic movement.
The acrylic crystal showcases a white sunburst dial with silver baton indices, a date window at 3 o’clock, and silver dauphine hour and minute hands. Our 62-year-old Slimdate came with a raw hide leather strap already attached to its 18 mm lugs when we acquired it a couple of years ago from our good friend and watch guru Jun Cajayon.
Model: Seikomatic Slimdate
Reference No. 841990
Month/Year of Manufacture: August 1964
Type: Dress Watch
Movement: Self-winding/Automatic
Caliber: 840
No. of Jewels: 30
Diameter: 36 mm
Thickness: 10 mm
Lug-to-lug Length: 40.8 mm
Lug Width: 18 mm
Weight: 30 grams
