MIL-STD-810G is an edition of the US military standard describing test methods for equipment resistance to environmental influences (shock, vibration, temperature, humidity, dust, low pressure, salt spray, solar radiation, etc.). It is not a central "certification" but a set of tests; the manufacturer usually indicates which methods and profiles were applied. Compliance can therefore vary. For watches and electronics, it often covers drops/shocks, vibration, thermal shock and humidity. The 810G designation indicates higher ruggedness than conventional consumer electronics, but not unlimited indestructibility - it always depends on the design and specific test configuration.