of additional water depth. Besides water resistance standards to a minimum of depth rating ISO 6425 also provides minimum requirements for mechanical diver's watches (quartz and digital watches have slightly differing readability requirements) such as: The presence of a time-preselecting device, for example a unidirectional rotating bezel or a digital display. Such a device shall be protected against inadvertent rotation or wrong manipulation. If it is a rotating bezel, it shall have a minute scale going up to 60 min. The markings on the dial, if existing, shall be coordinated with those of the preselecting device and shall be clearly visible. If the preselecting device is a digital display, it shall be clearly visible. The following items of the watch shall be legible at a distance of in the dark: time (the minute hand shall be clearly distinguishable from the hour hand); set time of the time-preselecting device; indication that the watch is running (This is usually indicated by a running second hand with a luminous tip or tail.); in the case of battery-powered watches, a battery end-of-life indication. The presence of an indication that the watch is running in total darkness. This is usually indicated by a running second hand with a luminous tip or tail. Magnetic resistance. This is tested by 3 expositions to a direct current magnetic field of 4 800 A/m. The watch must keep its accuracy to ±30 seconds/day as measured before the test despite the magnetic field. Shock resistance. This is tested by two shocks (one on the 9 o'clock side, and one to the crystal and perpendicular to the face). The shock is usually delivered by a hard plastic hammer mounted as a pendulum, so as to deliver a measured amount of energy, specifically, a 3 kg hammer with an impact velocity of 4.43 m/s. The change in rate allowed is ±60 seconds/day. Resistance to salty water. The watches under test shall be put in a 30 g/L NaCl (sodium chloride) solution and kept there for 24 hours at 18 to 25 °C. This test water solution has salinity comparable to normal seawater. After this test, the case and accessories shall be examined for any possible changes. Moving parts, particularly the rotating bezel, shall be checked for correct functioning. Resistance of attachments to an external force (strap/band solidity). This is tested by applying a force of 200 N (45 lbf) to each springbar