The BOSS LMB-3 is a limiter enhancer that improves the sound quality of your bass. It makes slap sounds sound cool. - Model Name: LMB-3 - Brand: BOSS - Type: Bass Limiter Enhancer - Color: Blue - Control Knobs: 4 knobs (MIN/MAX) Thank you for looking. I bought this used and used it a few times live. It has some scratches, but I've confirmed that it produces sound. No returns accepted.