These tubes are new old stock tubes and never used except when being tested and matched. They were made with East German precision at the original East German factory (so basically Telefunken). These are becoming very rare and come direct from Roger Modjeski at RAM Tubes. We recently discovered a box of 500 and will be putting the entire inventory up for sale. They are tested and matched by Roger himself in a way that makes sense when being used in an amp. Comes in original Siemens/Rohre box with test data label. Sold as matched quad only.