Cal. 6870 is an ultra-thin hand-winding two-handed movement produced by Seiko for Credor since 1993. It is derived from the 1973 Cal. 6810, which was used in a line of ultra-thin dress watches for Seiko, and remains similar to the original 1969 Cal. 68A. Other recent movements in the Cal. 68 family (Cal. 6890, 6898, 6899, and 6830) are quite different in design, with the balance wheel moved opposite the winding crown and a round rather than squared-off overall shape.
Cal. 6870 has been widely used in Credor models since the 1993 introduction. Notable watches powered by this movement include the 2001 110th Anniversary models and the 2002-present Credor UTD GBAQ series. It has also been used in the Credor Signo GBAQ line since 2007. From 2010 through 2012 it was used in the Credor Node GCAQ series.
