This is a Mackie DFX-12, a 12-channel analog mixer with built-in effects. I purchased it used on Yahoo Auctions. I am selling it to clear out my storage. I used it for adjusting the volume in my daily life. I moved about 4-5 years ago and changed my home environment, so I haven't used it since then. I haven't used the FX since I confirmed its operation, but it was working when I bought it. There are no missing knobs. Also, all the sliders are working properly. When I was using it back then, it was working normally without any crackling. I haven't used it for a long time, so I don't know the current condition. Since it has been left unused for a long time, there is a possibility that crackling may have started. Also, I have transported it twice due to moving. I haven't used it since the first transport. Due to the above reasons, it will be sold as-is. I do not guarantee its operation, so please purchase it with your understanding.