The IP67 certification is a standard which rates the degree of protection against water and dust by electronic material which has successfully passed the required tests.
« IP » means « Ingress Protection Rating » :
« 6 » this indicator means that the mobile phone is totally dustproof;
« 7 » this indicator means that the mobile phone can resist immersions up to 1 m without being damaged, and will also resist to relatively powerful water jets.
Those certifications are issued by the International Electrotechnical Commission (IEC's website).
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