Features: Suitable for surfaces mounted Piezo Pickup; This machine is a JFET high impedance charge type amplifiers circuit, which is not affected by the length of the input line and have no frictions effect; The builts-in lithium battery is rechargeable and can last for 10 hours on a single charge. Gains: When the capacitance value of the Piezo Pickup is 10nf, it is about 20db,The lower frequency limit is 30Hz Input impedance, greater than 10MΩ Specifications: Component:Metal Size:Approx.65x63x24mm/2.56x2.48x0.94inch Charging Interfaces: TYPE C DC5V Input/Output:6.35mm 1/4TS Output Impedance:600Ω Package Includes: 1pc Piezo Pickup Preamplifier note: Please allow 1mm errors due to manual measurement. Due to the differences between different monitors, the picture may not reflect the actual item color.