Water Resistance
If you spend a lot of time working outside or working out, make sure your buds feature at least some water resistance, ideally IPX4 or more. The higher the last number is, the better. You can swim on an IPX8 earbud, and an IPX7 rating will be able to handle submersion in three feet of water for up to 30 minutes. IPX4 is good for light splashes or some sweat. My Cleer Arc II buds feature an IPX5 water and sweat rating, and, on some days, I would even brush my teeth or wash my face without taking them off; they’ve been holding up just fine.
