The replaceable volume knob is compatible with the Fosi Audio V3 amplifier. To replace the knob, use a cloth for grip, firmly grasp the existing knob, and pull it straight off the shaft. Align the new knob with the shaft and press it firmly into place. Ensure the new knob is securely attached before use. Note: Due to different production batches, slight variations in appearance may occur. These differences do not affect functionality. Color: As shown Material: Aluminum alloy Package contents: 1 × Volume knob The package includes only the items listed above; other products are not included. Note: Lighting effects and monitor settings may cause slight color variations between the image and the actual item. Measurement error is permitted within +/- 1-3 cm.