depends on what kind, you could have head-band style with thin film over the surfaces and low power in ear transducers, i'd probably buy none (granted the pv fi

depends on what kind, you could have head-band style with thin film over the surfaces and low power in ear transducers, i'd probably buy none (granted the pv film doesn't degrade in a year) which reminds me that I regularly find old PV pocket calc, with I forgot what kind of oxide they used, still working fine..