Actually, the 6s still has a quite strong adhesive around the frame so if you accidentally drop it in water it should be fine... Apple refurbs ALWAYS come with the IP certificate, if there are any.
Unlike the iPhone 7, the 6s doesn't have gaskets around the SIM slot, speaker, headphone jack, sleep/wake, or volume buttons. You're really trying your luck if decide to introduce iPhone 6s to water.
What goes into a refurbished iPhone.
All refurbished iPhone models come with a new battery, new outer shell, are backed by a one-year warranty, have free delivery and returns, and also include:
Full functional testing, genuine Apple part replacements (if necessary), and a thorough cleaning
The original Operating System or a more recent version1
All refurbished devices are repackaged in a brand new box with all accessories and cables2
If your device is shipped with the original Operating System, the most recent version can be downloaded for free from the App Store.
Supply is limited and availability is guaranteed once we receive your full payment.
You probably didn’t miss out on much of a saving anyway. iPhones/iPads + the more expensive devices normally come with discounts that make refurbs worth your while.
You probably didn’t miss out on much of a saving anyway. iPhones/iPads + the more expensive devices normally come with discounts that make refurbs worth your while.