The TAD EL84M offers strong mids and defined bass response. Even, when played at lower volume or in a complex stage sound situation, your sound will prevail. This is the most reliable and longest-lasting military grade EL84 on the market and operates up to 10,000 hours. Unfortunately, this tube is not being produced anymore. Grab them, while they last! d= 22,5mm. Due to its diameter of 22.5mm, the TAD EL84-M does not fit into older Marshall DSL401 and UK made VOX AC15 TBX amplifiers.