Our experiences with bone conduction have been mixed; we didn't have fantastic results with Motorola's Endeavor HX1 Bluetooth headset but a brief play with music-centric headphones have been more impressive. So we're holding judgement on the Sanwa 400-HS015 Bluetooth sunglasses until we read a review: they hook up to your cellphone, PMP or notebook and stream stereo audio via the Bluetooth A2DP profile, but use bone-conduction rather than traditional in-ear buds.
By keeping your ears free of in-ear buds you can better hear traffic or conversations around you, reducing the likelihood of being run over by a bus or spanked by strangers. Instead, the audio is transmitted by vibrating the tiny bones of your inner ear, using two adjustable pads that sit just forward of your ears.
There's also a microphone for using the 400-HS015 as a Bluetooth hands-free kit, and volume controls (though no sign of remote control over whatever the music source is), while the lenses flip-up in case you need to wink dramatically. The Sanwa 400-HS015 bone-conduction Bluetooth sunglasses are available now, priced at 19,800 yen ($217).