Matched Pair Premium Grade Psvane 12AX7-T Mark  Vacuum Tube High-end in Gift Box Gold coated brass base to improve shielding to interference. Gold coated pins to enhance connection over long term. Can be used to replace Shuguang 12AX7-T directly. All parts are selected to the highest grade plus only highly experienced workers to assemble. Suggested burn-in time is 75 hours.