Motorola MOTO E Troubleshooting Manual page 9

The card will NOT be reformatted when
Portable storage is selected.
Performance warning
We recommend use of a high speed card , such as a UHS-1 type. Class 4 and Class 2 micro SD
cards are not recommended for adopted internal storage usage. The performance of these cards
is typically 10x slower than internal storage performance.
High speed card are identified by these logos:
If your card it too slow, your device will warn your during the adoption process. If you encounter
this dialog, we advise to upgrade your card to a UHS-1 card first.
Using your card as 'Portable Storage'

Insert the SD card on your device

Android will notify you a new SD Card has been detected, you can setup the card as portable or
internal storage
The card will be formatted when Portable
storage is selected.