This mini version of the Volbox makes volume adjustments quick and easy. Just pass your audio through. The knob is nice to grip and smooth when turned. You can keep it in a spot that's easy to reach, or mount it somewhere out of sight. The stereo input and output jacks are the common 3.5mm (1/8") size. No batteries are required. The Volbox Mini is hand built in Canada with good quality parts to provide many years of service. It has a tough ABS case that's held together with screws. It measures 35mm x 35mm x 15mm tall and weighs 17 grams. The knob pokes out 15mm and is about 10mm in diameter. You can pull off the knob and replace it with a bigger one if you prefer. Note: This will NOT make the volume louder than the music player's maximum level. For that you would need an amplifier. No cables are included. The Volbox includes a brief instruction card and uses minimal packaging to reduce the impact on our planet. Please contact me through Amazon at any time if you have questions about using the Volbox in your system and I will be happy to help you. -Clark