Behringer UW300 Ultimate Auto-Wah Effects Killer wah pedaloffers auto-wah effects for all styles and sounds Control the wah effect with your string-picking strength and add an awesome funky touch with the modulation wah Blue status LED for effect on/off and battery check Runs on 9 V battery or the BEHRINGER PSU-SB DC power supply (not included) First-class electronic On/Off switch for highest signal integrity in bypass mode