SPECIFICATIONS
MovementAutomatic mechanical with alarm, Seiko 4006/4006A, 17–27 jewels, 19,800 bph.
Caliber4006 / 4006A
Case size~37.5–38 mmmm
Case materialStainless steel
Case shapeMostly round / slightly tonneau; special UFO/cushion variants exist.
ThicknessTypically about 13–14 mmmm
Lug widthCommonly 18–20 mm; some proprietary widths (e.g., 19.5 mm, 23 mm)mm
CrystalAcrylic with tension ring
Dial colorMultiple colors including white, black, bright blue, blue-gold, black-red
ComplicationsDay-date, mechanical alarm with ~10–11 second ring
Release year1966
Seiko
Bellmatic
Seiko Bell-Matic models share a core set of technical traits such as automatic mechanical movement with integrated mechanical alarm, materials, but dimensions and some details vary by reference. The specifications below describe the typical Bell-Matic 4006 series.