Sony announced a new In-Ear headset with a 13.5mm sound driver dubbed MDR-EX90SL.

Obviously you would not be able to fit a 13.5mm speaker inside you ear channel. Sony came up with a swivel design (see diagram below), that enables you to wear these large sound drivers. The larger speaker provides for a wider dynamic range. Specifications of the Sony MDR-EX90SL include a 5-25,000Hz frequency spectrum, 16Ohm impedance and a weight of 7g.
Sony will start selling the MDR-EX90SL starting May 10th for 12,390 yen (~$104).
Find more background information in this Sony press-release (Japanese). Research Sony Headset deals.