What's in the box:

HA400 Ultra-compact 4 Channels Mini Audio Stereo Headphone Amplifer with Power Adapter (Black Red)

Features:
Ultra-compact stereo headphone amplifier for studio and stage application.
With 4 headphone output channels and 1 input channel.
Volume of each output channel can be controlled independently.
Provides highest audio quality for each headphone even at maximum volume.
Ultra low noise 4580 operational amplifier for outstanding audio performance.
Comes with a DC 12V power adapter.

Specifications:
Material: Metal
Color: Silver
Power Adapter: EU Plug
Item Size: Approx. 10.5 * 5.5 * 4.5cm / 4.1 * 2.2 * 1.8in
Item Weight: 185g / 6.5oz
Package Size: 22.5 * 14 * 8.5cm / 8.9 * 5.5 * 3.3in
Package Weight: 385g / 13.6oz

Package List:
1 * Amplifier
1 * Power Adapter
1 * User Manual (English)