1Passive Volume Controller: This volume controller adopts only 1 pair of RCA interface for input and output, simple and easy to use. Plug and play, no need for power supply. 2Premium Material: The passive volume controller is made of all metal material, with fine workmanship, anti interference, rust prevention, sturdy, and lasting. 3Stable Performance: The passive preamp speaker volume controller has stable signal transmission and clear, pure output audio. Suitable for home or professional recording studio use. 4Compact and Portable: With size of 16.7x6.8x4.9cm, this volume adjuster is compact and lightweight, allowing you to enjoy wonderful music anytime, anywhere. 5Lossless Output Design: The passive preamp volume controller features smoothly and transparent sound quality design, allowing you to easily enjoy wonderful music. 1 x Passive Volume Controller 1 x Instruction Manual