Acer B1-721 - Manual (Page 7)

Using your tablet - 7
U
SING YOUR TABLET
Using the SIM card slot
Certain tablets include a SIM slot for internet access. To take full
advantage of your tablet’s Internet capabilities, you should install a
SIM card with data subscription before turning on your tablet.
Charging your tablet
For first-time use, you need to charge your tablet for four hours. After
that you can recharge the battery as needed.
Assembling the power adapter
Slide the large end of the USB cable into the power adapter body (it
will fit in only one direction).
Note
Charger illustration is for reference only. Actual configuration may vary.