This is the T-REX Auto Wah, released as part of the TONEBUG series. The main feature is the central toggle switch, which allows you to switch between WAH WAH and YOY YOY sounds. WAH WAH offers a traditional sound, according to the manual. When SENSE and RANGE are set to maximum, it has a similar effect to the Guyatone WAH ROCKER, just before it gets extreme. I think it's a practical range. YOY YOY has a more high-frequency range and a distinctive sound. It's difficult to describe, but it's like a "quacked" sound. When used with distortion rather than clean, it sounds like a talking wah. It works with both an adapter and batteries. The accessories are as shown in the photos. It's in relatively good condition, but there are traces of removed Velcro on the back, and the rubber is slightly lifted. Thank you.