HTC One E8 - Manual (Page 12)

Also, if you want to use a protective case, make sure to buy a case that's designed for HTC One (E8)
and that doesn't block the trays.
nano SIM card
HTC One (E8) uses a nano SIM card.
Use a standard nano SIM card only. Inserting a modified card that is thicker than the standard
nano SIM card may cause the card to not fit properly or damage the card slot.
Inserting a nano SIM card
1. Hold the phone face up.
2. Insert the tip of the tray eject tool (or a small bent paperclip) into the tray eject hole next to
the nano SIM card slot.
3. Push the tip all the way into the hole until the tray ejects, and then pull the tray out.
4. Remove the placeholder card from the tray, if there's one pre-inserted.
12 Unboxing