Description : Adopts NE5532 front chip for for better performance . High quality potentiometer contacts well , stable for audio output . PCB with 1 . 6mm thick double - sided sheet thickness of 2 . 0 oz copper spray tin process , to ensure the size of the current good performance , excellent quality of the PCB . The fully enclosed dust potentiometer , performance is more stable , more durable than the ordinary potentiometer . Alignment of the entire circuit board layout is very strict and reasonable , the overall PCB traces with little grounding method . Stable and reliable , steady and low - frequency strong signal to noise ratio is very good , wide dynamic range ; clear details , excellent transient response and play a variety of music to the occasion , a very good performance in the playback environment of the family . Specification : Material : ABS + Metal Panel size : Approx 90mm * 23mm Center hole distance : 35MM Operating voltage : DC / AC 9V - 30V Number of Channel : Dual - channel Audio Package Includes : 1 Piece NE5532 Preamplifier Board 2 Pieces Lines Note : Please allow 0 . 5 - 1 inch difference due to manual measurement .( 1 inch = 2 . 54cm ) Please check the size measurement and the picture carefully before making payment . Due to the difference between different monitors , the picture may not reflect the actual color of the item . Please understand , Thank you .