SEIKO Square Case Perpetual Calendar Black Dial Men's Quartz Watch 5Y66-0AC0 | eBay
Sold at Auction: A Vintage Seiko 5Y66 Quartz Chronograph Gents Watch. Black leather strap. Stainless steel case - 40mm. Black dial with three sub dials. In good condition and working order.
SEIKO 5Y66-0AB0 Quartz Watch | WatchCharts
Seiko - Retrograde *Perpetual Day* - Original Strap - SNT007 / 5Y66-0AC0 - Men - 2011-present - Catawiki