The PYD3808 from Pyle Pro is a 4-channel DJ mixer. It features inputs for multiple sound sources (CD players, MP3 players, vinyl turntables, microphones, etc.), and it enables the operator to blend these different audio signals together. The PYD3808 can be mounted in a 19" rack and features a built-in digital sampler with sample pitch adjustment and cue functionality.
The main outputs of the PYD3808 feature balanced 1/4" TRS jacks. Typically these outputs will be plugged into a sound system, such as a PA amplifier or powered speakers. The PYD3808 also features a 1/4" headphone output with cue functionality on each channel. Engaging cue will allow you to hear the audio on that channel through the headphones, without sending that audio to the main outputs. This way you can cue up sounds before you share them with the audience.
The PYD3808 comes with all of the controls needed to cover a wide range of DJing and mixing duties. Its 19" rack-mountable form factor is often preferred by professional mobile DJ's. It comes with a 2 year manufacturer's warranty.