OnePlus is about to announce something on 17th December but it seems that nobody knows what it is. Based on the teaser posted on their Google+ account, it says “Go Further” with 4 LEDs on it.
In my opinion, it might be just an accessory announcement (I might be wrong, of course). However, the tagline “Go Further” goes well with a Portable Battery and the 4 LEDs seems to be common on such devices to indicate the battery level.
Some says that it might be OnePlus One mini (which is still a rumor). What do you think? I will go with the accessory.