Where is the magnet located on the Q10?

This may be a really silly question, but where is the magical magnet that controls the holster profiles located on the Q10?

Also, a related question -- I've seen a lot of people comment that if you get the official BB holster with belt clip, the holster is actually a little loose and you can actually put a second skin/case on your Q10 and it will still fit. Does putting on the second skin/case interfere with the magnet features of the holster?

It's at the center of the screen, at the bottom 2 cm right above the T and Y keys. You can activate it through the battery side, but the sensor itself is closer to the front of the phone. In the OEM holster, if you place the phone in as designed, with the glass facing the clip and the power button facing up, I don't think a case would affect the magnet.