This is a used Korg PX4 (blue), an extremely popular ultra-compact multi-effects unit from the early 2000s. The items for sale are the main unit, strap holder, and adapter, as shown in the photos. This model, which uses Korg's "REMS" modeling technology, remained popular even after it was discontinued due to its excellent sound quality. You can still find reviews online today. The output can be stereo, either to headphones or an amplifier/audio system. For personal practice, it has a built-in rhythm machine and a 3.5mm AUX input for simultaneous input of audio sources like an iPod. The "slightly problematic" aspects are that the input level switch, which is set according to the guitar's output, is broken and cannot be switched, and the value knob sometimes jumps values when turned. While there should be little to no hindrance to use, please consider this before purchasing. Other functions have been confirmed to work normally, and there are no major scratches or stains, but please understand that this is a used item. The items for sale are the main unit, strap holder, and adapter, as shown in the photos. The instruction manual can be found by searching for "PX4_EFGJ3.pdf," which supports multiple languages, including Japanese. Immediate purchase is welcome. I cannot answer questions about the specifications.