Higher B+ voltage. 201.5v B+ +/-1.5%. That means more headroom.
NOS 12AX7A vacuum tube for warmer tone and more focused mids.
Tube damper installed to minimize microphonic noise and provide added shock resiliency.
Components extensively tested and sorted. In the Certified Premium version only the top 1% components are used... selected for high performance. That's how we get the higher B+ voltage with a smaller tolerance between pedals. It also helps to lower the noise floor.
Each pedal comes numbered and labeled with the exact B+ voltage of that pedal (written on inside of lid). On the back of the lid is a "Certified Premium" hologram sticker. Each box has a Certified Premium Sticker on it. The included 5-year warranty card says its a "Thunder Knob - Premium."