The Silver Series 12AX7 from Groove Tubes

From Groove Tubes:

"Groove Tubes Silver Series are tested and warranteed to meet or exceed factory specifications but are not sold in matched sets or premium selected grades as are our traditional Groove Tubes product line.

Silver Series tubes are excellent for "normal" tube replacement applications and offer exceptional value.

We do not recommend these for the critical high gain V1 stages of high gain guitar amps, but we do recommend these for the other less critical stages such as V2-V6 stages.

If you need a selected low noise, non microphonic tube for your V1 high gain stages, please choose a hand selected ultra premium tube from our traditional Groove Tubes preamp tube selection."

Price is for a singe tube.