Seiko RC-4500 Data-Graph smart watch from 1985

In outstanding condition 

Black stainless steel version 

New battery and fully serviced

this one is the best looking version, very rare!

The Seiko S521-4020 (often designated as the Seiko RC-4500) is an incredibly rare, vintage digital "PC Datagraph" smart wrist terminal originally released by Seiko in 1985.

Dubbed one of the "world's smallest computer terminals," it belongs to Seiko's legendary line of 1980s wearable computer watches

• Movement/Module: Seiko S521 quartz digital calibre. 
• Display: A unique three-line dot-matrix LCD. The bottom line is prominently larger and reserved for displaying the time, while the top two lines display text data. 
• Storage Capacity: 2KB of internal RAM storage used to hold memos, schedules, and database entries. 
• Connectivity: It features a specialized side-terminal port designed to connect via a proprietary cable to popular 1980s PCs (such as the Apple II series, Commodore 64, and IBM PC) to sync data using floppy-disk software.
• Case & Material: Stainless steel or base-metal rectangular case with integrated bracelet options