Item Type: Tremolo EffectMaterial: MetalColor: KhakiInput Impedance: 1MOutput Impedance: 1KProduct Power Supply: 1 x carbon dry battery 9V 300mAh (built in battery) or DC 9V power adapter (not included) 1Tremolo Effect: The tremolo effect is similar to the classic tremolo embedded in the amplifier of the 60s. 2Special Circuit: With special circuit that can produce high quality vibrato effects and has a wide operating range. 33 Adjustment Knobs: Tremolo effect has 3 adjustment knobs, namely Rate, Wave and Depth, which are powerful and practical. 4Metal Shell: The guitar effect shell is made of excellent metal material, hard and wear resistant, can be used for a long time. 5Compact Size: The guitar tremolo effect is small and compact, light in weight, space saving and easy to carry.