Classic Stax SR-3 electrostatic headphones which were introduced in 1968.  Great sounding headphones and they need a 6 pin Stax amplifier or energizer.  Warm and mellow sounding with plenty of extension.  

Used set in good working condition.  They are discolored and a bit rough looking but charge up instantly and sound balanced to my ears.  

The headphone stand pictured is not included