This is our Tweed Option Retube Kit for the Blackstar HT1 series amps. It contains a JJ 12AY7 for V1, and a Balanced ECC82 for power. The Tweed Option will drop the gain down a bit more than the SRV Option allowing you to get more power tube breakup at higher volumes. The JJ 12AY7 has a fat warm tone with a big shimmering sparkle in the high end!