This sale is for a pair of Voxativ AC-X field coil drive units, these utilize electromagnets instead of permanent magnets.They require an energising voltage of 12 - 18 volts DC at approximately 1 amp ( per driver) Power supplies are not included in this sale, however they work best with heavy duty 12 volt batteries.2 x 4 metre cables will be supplied with correct plugs for connecting the DC voltage to these drive units. Compared to permanent magnets, field coils give a more natural soundstage, more speed and less distortion.I would be pleased to demonstrate these drive units at my home in East Sussex to any prospective serious buyer.Please see the Voxativ website where it gives full details, specifications and prices.The latest retail price from Voxativ in Berlin is 13,900.00 US dollars = £11043.48 per pair plus VAT = £13,252.17 ( plus shipping). Both drivers are in perfect working order both physically and electrically, no distortion, no buzzing and no foam deterioration.When partnered with suitable horn cabinets these drivers can sound truly spectacular and with real Bass ! Manufacturers specifications :-Frequency response 20 Hz - 20 KHzPower handling 50 watts nominal 100 watts musicVoice coil impedance 10.5 ohmsWeight ( each unit ) 12 kg Due to weight I would prefer for collection only as these drive units and the wooden packaging boxes will be very heavy. By arrangement i would be happy to deliver within 50 miles of my home address in East Sussex or for the items to be shipped on a pallet. Alternatively I will be at the UK Hi Fi show at Ascot racecourse 29th September to 1st October and these drive units could be collected from there by prior arrangement. Please see my other listings for more vintage loudspeakers