Description: 4 Bands 7545R equalizer system perfect for standard acoustic guitar or box guitar. Curved surface fits the curved side of a standard acoustic guitar. 4 Bands (Bass/Middle//Presence ) control built-in battery holder for 9- battery (not included) low battery indicator. The rod piezo ceramic offers great and pickup range and is mounted beneath the saddle of a standard acoustic guitar but it can be easily built into a box guitar bridge as Pre- for easy assembly connecting wire with 6.35mm(1/4 inch) output . Size Chart: Size: 22 x 14 x 5.5cm / 8.7 x 5.5 x 2.2in Package Includes: 1set 4 Band EQ Equalizer Note: Please allow 1-3mm measuring deviation due to manual measurement. Due to the different monitor and light effect the actual color of the item might be slightly different from the color showed on the pictures.Thank you!