THESE ARE FACTORY PLATINUM MATCHED AND BURNED IN. WE DO NOT TREAT OUR TUBES WITH ANY PROCESSES THAT WILL COMPROMISE TUBE LIFE AND SOUND QUALITY.YOU GET TUBES STRAIGHT FROM THE FACTORY AS THEY ARE INTENDED TO BE. This listing is for (4) brand new, factory fresh, TUNG-SOL 6550 as a closely Factory Matched Quad. The factory box stickers hold the data for each tube. Unlike our competitors, we are a full service company, offering parts, tubes, equipment and repair services. We are not just tube resellers but are technically qualified to service the equipment they are used in, and to answer your technical questions as well as provide technical assistance when the need arises. This item is in the category "Consumer Electronics\Vintage Electronics\Vintage Audio & Video\Vintage Parts & Accessories\Vintage Tubes & Tube Sockets". The seller is "ctech-electronics-store" and is located in this country: US. This item can be shipped worldwide.