Need a few good used 7199 tubes for testing or to replace that original Dynaco one in your Mark IV? Here you go! A good price on some rare, but popular preamp tubes widely used in Dynaco equipment. All three are "Made in U.S.A." and look to be in great shape! My tube tester does not have the 7199 on it and I sure don't own a vacuum tube curve tracer, so I really can't test them except in my Dynaco Mark IV to make sure they just plain work. I can't make any guarantees about how much life they have left, so buy at your own risk.