Mesa always delivers top quality tubes, my friend uses them almost 20 years now, no complaints ever. Advice is to only use Mesa tubes on Mesa amplifiers cause they are fixed biased. In fact, although they are expensive, I would advise their use in all amplifiers, because of their top quality.
Thank you Thomann once more, although there was a shortage in this kind of valve, and took some time to get back in stock and ship, Thomann always delivers! Excellent customer service, excellent shop!