Neewer 9V Power Adapter with Tip Negative Design and 300mA Max Current, Works with Effects Pedals/Units, Tuners, Amplifiers, Compressors or Other Devices Require Tip Negative 9V Well-constructed and compact power adapter has a 9V 300mA output. Tip negative(-) design. This adapter has the + (positive) side on the outside, and the - (negative) on the inside. PLEASE MAKE SURE you check the right POLARITY before ordering. Capable of powering a variety of effects pedals/units, tuners, amplifiers, compressors or other devices require tip negative 9V. Reliable power supply, simple and effective, just plug it in, with no buzz or hum noises. Can also be used to power additional 9V tip negative effects pedals. NOTE: Pedal in the picture NOT INCLUDED.