Fangrui Product Details Operating Voltage: Recommended Ac Double Ac22-26v Output Peak: 250w + 250w Output Load: 4-8 Ohm Output Impedance: 30k Ohm Color: Green Material: Metal Total Harmonic Distortion: Less Than 0. Frequency Response: 10hz-20hz Signal To Noise Ratio: 90db Weight : 473g Power Amplifier Tube Model: 2sk385 Size : 15.8 X16.7 X 4.2 Cm Using High-power Output Tube To Do After-level Drive, With A Variety Of Speakers, The Output Power, The Latest Pcb Software Design, To Ensure That The Circuit Is Stable And Improve Signal-to-noise Ratio. Application Of Digital Delay Reverberation, And With Tone Control, Easy To Install. Package: 1pcs Audio Amplifier Board Only The Above Package Content, Other Products Are Not Included. Note: Light Shooting And Different Displays May Cause The Color Of The Item In The Picture A Little Different From The Real Thing. The Measurement Allowed Error Is +/- 1-3cm. Note: Due to the light and screen setting difference, the item's color may be slightly different from the pictures. Please allow slight dimension difference due to different manual measurement.