That link was for the G Watch which is rated for water and dust resistance. You can just make your phone ip67 proof that easily there's a lot involved, the speaker for one has a nano water resistant coating of I remember correctly . ip67 is a lot harder to get than you think, the Z2 is only ip55 or 58? Which is lower than the 67 of the s5, but Sony has a higher water rating allowing it to be submerged deeper for a longer time.

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