Cal. STP8-14-21 is a compact automatic watch movement usually used in ladies watches. Introduced by Swiss Timing Production (STP) in 2016 it no longer appeared in the company’s catalog after 2017. It is 7.75 ligne (17.20 mm) in diameter and 5.34 mm thick. Cal. STP8-14-21 operates at 21,600 A/h and is similar to the ETA 2650.
Cal. STP8-14-11 and STP8-14-21 are very similar apart from the date complication (in the former) and corresponding 0.58 mm difference in thickness.