Sea-Master-300

42mm rotatable bezel, 904L bracelet, sapphire crystal, luminous hands,built-in 8215(or Swis-8900) automatic winding movement, 40-hour power reserve, watch weight approximately 166g (steel version), extremely high cost-performance ratio, It absolutely doesn't feel cheap for $200 when worn on the wrist.Come with brand box, pendant, and original papers.

Sea-Master-600

Automatic winding top version. Made of 904L steel, with a ceramic rotating bezel, sapphire crystal, and a steel bracelet. The bracelet version weighs approximately 180g and is suitable for wrist sizes between 18-22cm. Buit in Swis-9300 or 9900 movement.Through the transparent watch back, the double T black balance wheel movement is visible.

SpeedMaster Chronograph

The models priced around $200 USD feature quartz movements, while those priced around $500 USD are equipped with either Swis-9300 or 9900 self-winding automatic movements top version.Made of 904L steel, with a ceramic rotating bezel, sapphire crystal, and a steel bracelet. The bracelet version weighs approximately 180g and is suitable for wrist sizes between 18-22cm. 
With chronograph function: when you press the upper button on the right side of the watch, the second hand begins to move. Pressing it again stops the second hand. Pressing the lower button on the right side resets the second hand to its initial position. Regardless of whether the second hand is moving, the hour and minute hands continue to run normally. Therefore, the second hand typically remains stationary.