This connector is for use in general audio application. It is used with balanced signal and its diameter is 3.5 mm.
Pin designation,
Positive Signal: Tip, Return Signal: Ring, Shield: Sleeve.

Normally, this kind o connection is used in smartphones or tablets as headphone outputs. In such case, is an unbalanced and stereo connection.

Pin designation,

Left: Tip, Right: Ring, Shield: Sleeve.

Bibliography: AES-R3-2001,IEC 60603.