The X2 Hybrid Headphones look common enough, but look closer. They double as speakers. It allows you to switch back and forth between headphones or external speakers. If your ears get tired, just switch them. The outside of the earcups functions as the external speaker and the interior earcups function as a normal pair of headphones. Pretty neat design.
The drivers are 40mm and as speakers they output 0.5 watts. When used as a speaker they need to be charged and will operate for 4 hours on a 1 hour charge. They also come with a 3.5mm stereo gold plated plug and a 6.3mm stereo plug.