Seiko Astron SSJ012J1

The Seiko Astron SSJ012J1 takes a 21 mm watch band.

Seiko · Astron

21mm

lug width

Bands that fit

Cut and stitched in Milano, in the width this watch takes.

Any 21 mm band fits this reference, in leather, rubber or fabric.
21 mm is an odd size: most ready-made bands are made in even widths, so this reference needs one cut to measure or a band that runs in odd sizes. Why some watches take odd sizes →
Inside the Astron family the lug width is not one number: it runs 14, 21 mm. This reference is the 21 mm one, so a band bought for another Astron may not fit it. Why the size changes inside a family →
21 mm is not a common size: only 2,956 of the 41,485 watches measured take it (7.1%), so ready-made choice at this width is narrower than at 20 or 22 mm. Every watch that takes 21 mm →