|Brand:||Seiko, Seiko Instruments Inc., Time Module Inc.|
|Winding:||Automatic, Bi-Directional Automatic Winding|
|Diameter:||27.40 mm (12 ligne)|
|Complications:||Date, Date by Pointer, Day, Day by Pointer, Hacking Seconds, Hand Winding, Power Reserve Indicator, Quick Date Correction, Quick Day Correction|
|Hands:||Central Hour Hand, Central Minute Hand, Central Seconds Hand, Date Pointer at 6:00, Day Pointer at 3:00, Power Reserve Pointer at 9:00|
|Production: 2009 – Current|
Seiko Cal. 6R21 is a midrange automatic movement produced by Seiko Instruments Inc. (SII) for Seiko watches. Since 2010, it is also sold by Time Module Inc. (TMI) as Cal. NE20 (or NE20B) for use by other manufacturers. Like other Seiko 6R movements, it is more refined and accurate than the related Seiko 4R series and uses a Spron 510 mainspring. Unlike Cal. 6R15, it is a “Hi-Beat” movement operating at 28,800 A/h and has complications: Subdial day by pointer at 3:00, subdial date by pointer at 6:00, and counter-clockwise power reserve at 9:00.
Cal. 6R21 was introduced around 2009 and remains in production today. It has 29 jewels and 208 parts. Cal. 6R21 was used in the Ananta Multi-Hand Automatic watches, models SPB017J1, SPB019J1, and SPB021J1, produced August 2009 through March 2013.
|6R20||29||208||28,800||Day Subdial||Date Subdial||Clockwise|
|6R21||29||208||28,800||Day Subdial||Date Subdial||Counter-Clockwise|
|6R24||31||224||28,800||Retrograde Day||Retrograde Date||Clockwise|