This is the MXR microamp plus. It's a booster for guitar, but it can also be used for bass. I'm listing it with tears in my eyes to raise funds. I was using it until recently, so there are some minor scratches, but there are no problems with its operation. The box is also included. The MXR Customshop CSP233 Micro Amp +, which was discontinued despite its popularity, has made a comeback as a regular MXR product. The classic booster MXR Micro Amp has been tuned up for better usability. While retaining the gain boost of the Micro Amp, it uses a low-noise OP amp for lower noise. Bass & Treble EQ has been added, allowing for a wider range of sound creation. Power: 9V: 006P/9V battery or 9V AC/DC adapter Dimensions: 59(W)mm × 111(D)mm × 48(H)mm Type...Electric Guitar Manufacturer...MXR