New old stock 1970's vintage military issue British made Mullard CV2371 DF61 6611 tubes. This is a low voltage (operates on as little as 30 volts DC plate/anode voltage, so could operate directly off 48 volt phantom power supply lines) subminiature broadband pentode. Offers on this item considered for quantity 50 or more. This item is shipped from Britain, in North America or Asia please allow 2 to 3 weeks for delivery. The filament operates from 1.25 volts at only 20 milliamps, so could be supplied from an ordinary dry cell or alkaline battery.