100 percent Brand new and high quality Input: AC 12V 1A 5.5x2.5 plug Channels: 2.0/stereo Potentiometer function: Volume adjustment and switch FE-6J1-2 tube preamp board is designed based on the circuit schematic of the Music Fax X-10D, optimized for improved stability and 10 percent better tube performance. It uses a single 12V AC input to provide the required positive/negative voltage and filament supply for the 6J1 tube. Operation: The tube filament heats up when powered, with a clean power supply system (8x470uF capacitor filtering). The DC filament reduces noise. Color: As shown Material: Plastic and metal Size: 77mm x 75mm x 52mm Package includes: 1x 6J1 tube preamp board 1x Transparent shell 1x Instruction manual 1x Screw set Note: DIY assembly required. Package contents only, no additional items. Color may vary slightly due to lighting/screen differences. Size tolerance: 1-3cm.