Ball CM1011C Railroader Chronograph Quartz Case: 39mm Thickness: 12.5mm Lume: T25 WR: 100m A Quartz Ball made with an ETA movement. The ETA 251.471 23-Jewel Quartz chronograph movement is a quality quartz which has some unique features. 1. A 1/10th second dial that allows for pretty precise timing, certainly more precise than one normally needs. 2. It features a quick time-zone change function that is part of the date setting function. When the crown pulled out one stop (A position), you can jump forward a full hour at a time without affecting the minutes, hence time-zone change. To change the date, continue turning 24hr until you have the right date. Stop at the hour prior and adjust the minute hand forward by pulling the crown out fully. The 251.471 has an estimated 24 month battery life and an accuracy of +/- 15 seconds a month.