Features 4-channel: Relay type 4-channel audio source selection, switching, input selection board (actual 1-4 way adjustment). Easy to Switch: You can switch CD/DVD/PHONO/AUX 4 sets of input, and set LED lighting tube for switch shift indication. Long Service Life: The relay used is well-selected relay , durable and reliable, which has long service life. 1.6mm Thick Circuit Board: With 1.6mm thick double-sided tinned printed circuit board, the most direct and most fidelity switching of the sound source, the board is stereo two-channel. Cable Long 30cm: Motherboard and switch connected with cable long 30cm with knob. Specification: Item Type:Audio Switch Input Board Single Power Voltage:AC12~15V Development Board Size:43.5 x 43.5mm / 1.71 x 1.71in Installation Hole:33.5 x 33.5mm / 1.32 x 1.32in Motherboard Size:105 x 43.5mm / 4.13 x 1.71in Installation Hole:94 x 33.5mm / 3.7 x 1.32in Base Hole Interval:13mm / 0.51in Package List: 1 x Audio Source Selection Board 1 x Selection Switch 1 x Connection Cord 1 x Knob 2 Bag of Accessory Package List 1 x Audio Source Selection Board 1 x Selection Switch 1 x Connection Cord 1 x Knob 2 Bag of Accessory