I bought this watch with a bit of suspicion. But for the price risk was not excessive. I wanted a spare watch my Swiss watch brand (R ... X). I did a few days ago and I could verify its excellent precision: it takes only 3 seconds per day, which is, to my great surprise, better than my watch brand! This clarification is consistent with the tolerance for certified COSC chronometer according to standards. It is large: 2mm more than the R ... X (see attached photo). Its construction seems to be of excellent quality. I am totally satisfied.