Asus T300LA - Manual (Page 22)

 Notebook PC E-Manual
Left Side
The following hardware features located on your touch screen panel
and PC dock can be used while working on your Notebook PC.
NOTE: The following hardware features on the touch screen panel also
work when using the device as a tablet.
USB 3.0 port
This Universal Serial Bus 3.0 (USB 3.0) port provides a transfer
rate of up to  Gbit/s and is backward compatible to USB .0.
Headphone output/microphone input combo jack port
This port allows you to connect the touch screen panel to
amplified speakers or headphones. You can also use this port to
connect your touch screen panel to an external microphone.