The Citizen Promaster Marine Automatic Diver Challenge NY0121-09XE watch impresses with its pure diver's design and, of course, also with its features such as durability or compliance with ISO 6425. However, it will serve you well not only during dives, but also during everyday wear. The Citizen Promaster Marine Automatic Diver Challenge NY0121-09XE watch impresses with its pure diver's design and, of course, also with its features such as durability or compliance with ISO 6425. However, it will serve you well not only during dives, but also during everyday wear. The case of the Citizen NY0121-09XE is made of stainless steel and is complemented by a rubber strap. The case houses Citizen'smechanical in-housemovement 8204 with automatic winding and a hacking function - stopping the seconds hand on command. The movement operates at a frequency of 21,600 semi-frequencies per hour (3Hz) and has 21 stone fits. This movement also features the Parashock system (a Citizen invention), which increases the movement's resistance to shock and jolts. A handy feature is the date and day of the week display, located at the traditional 3 o'clock position. The clear dial, whose legibility in the dark is facilitated by luminescence on the hands and indexes, is protected by a sapphire crystal. The glass is therefore extremely scratch-resistant. The water resistance of this model, supported by a screw-down crown, is 200m, so it can easily handle diving or swimming. A unidirectional rotating diving lunette is used to measure time periods. The watch complies with the ISO 6425 diving standard, which can be recognized by theDiver' s inscription on the dial. These watches must have a water resistance of at least 100 metres, and each piece must be pressure tested to 125% of the declared water resistance value (i.