Feature: 1. WIDE COMPATIBILITY: Piezo pickup preamplifier is applicable for Guitar, Cello violin, Ukulele, Mandolin and other stringed instruments, Suitable for surface mounted piezo pickups. With 6.35mm sound cable. 2. HIGH IMPEDANCE CIRCUIT: Piezo pickup preamp adopts JFET high impedance charge type amplifier circuit, built in piezoelectric ceramic chip, not affected by input cable length, ensuring no friction effect. 3. GAIN FUNCTION: When the capacitance value of the piezo pickup is 10nf, about 20db, the lower frequency limit is 30Hz, the input impedance is more than 10MΩ, the output impedance is 600Ω 4. RECHARGEABLE BATTERY: The piezo pickup preamp features a built in 300mAh rechargeable li ion battery, with Type C charging cable, providing up to 10 hours of continuous use on a single charge. 5. ALUMINUM ALLOY DESIGN: Constructed from premium aluminum alloy, our piezo pickup amplifier ensures durability and portability. It's robust yet compact, making it the nice companion for musicians on the go. Specification: Item Type: Piezo Pickup Preamplifier Material: Aluminum Alloy Battery: Li ion Polymer Battery (Built in) Capacity: 300mAh Battery Life: 10 Hours Charging Interface: TYPE C 5V Input/Output: 6.35mm 1/4TS Output Impedance: 600Ω. Package List: 1 x Piezo Pickup Preamp 1 x 6.35mm Sound Cable 1 x USB Cable