These very unique cufflinks are anatomically correct (scale: 100%) models of the inner ear -- the small bony organ inside the skull that's responsible for our sense of hearing and balance, and is composed of the cochlea and semicircular canals. The two cufflinks are mirror versions of each other - just as the two inside the skull are, and come labeled as right and left. These make a great one-of-a-kind guy gift for someone in acoustics, audiology, or music. Note: these cufflinks do not have gears on them, and 'work' very simply by slipping and angling the rod and bar through the cufflink hole. The 'rod' (perpendicular to inner ear) stretches out .9 mm before intersecting with the bar. The 'bar' (horizontal to inner ear) measures 1.3 cm in width. Thanks for looking!