The Korg Nutube 6P1 is a newly developed vacuum tube.  It is a dual, directly heated triode intended for audio use.  It uses very little power, and can be used in battery powered applications. For more information, please visit the Nutube US website (in their infinite wisdom, eBay no longer permits me to post the link here, so you will need to do a web search). Flat rate shipping via FedEx to US destinations is shown.