Revue Thommen was founded in 1853 by Gedeon Thommen and has since developed into one of the leading Swiss watch companies. Early on, only wristwatches and pocket watches were produced and they relied exclusively on their own movements. In the 1920s Revue Thommen also started producing instruments for the aviation industry. This segment was constantly expanded, and today, Revue Thommen's instruments are among the leading products in the aviation industry. Case: Stainless Steel, Round Caseback: Stainless steel, Screw-down, Solid Bezel: Stainless Steel, Blue, Uni-Directional Dial: Blue, analog Hands: Silvertone Markers: Luminescent, Dots, Silvertone Calendar: Magnified Date display window at the 3 o'clock position Functions: Hour, Minute, Second, Date Strap: Rubber, Black Clasp: Deployment, Stainless Steel Crystal: Sapphire Crown: Stainless Steel, Screw-down Movement: SW200 Automatic Movement, 28‘800 oscillations Water Resistance: 30 atm/300 meters/1000 feet Power Reserve: 38 hours Case measurements: 42 mm in diameter x 12.65 mm thick Strap measurements: 22 mm wide x 8 in long Country of Origin: Switzerland Model: 17571.2828 All measurements are approximate and may vary slightly from the listed dimensions.Men's watch bands can be sized to fit 7.5-inch to 8.5-inch wrists. Extra links are available through the manufacturer. (We do not provide this service).Automatic movement winds with the movement of your arm. It is recommended that you wind the watch every two weeks.A screw-down crown (knob) creates a water-resistant seal. To unscrew the crown, turn counter-clockwise and pull/push into position to set time, date, and other functions. To close the crown, press it against the case and turn clockwise.