● This is a booster that uses vacuum tubes. It adds the sound pressure and a slight boost characteristic of vacuum tubes to the original sound. ● This listing will include a 12AT7 tube. You can also use 12AU7, 12AV7, and 12AX7 tubes, so try different tubes you have to find your favorite sound. ● Although it's a booster, it's set to be almost a buffer at the 10 o'clock position to prevent distortion even when clean. ● Because it uses vacuum tubes, it will produce some hum noise compared to a transistor natural booster, but this is not a defect. ● When placed after a tube screamer, you can enjoy the nuances of a vacuum tube even with a transistor amplifier. ● Recommended for those who feel the sound is thin with line input. Currently used in recordings by many studio musicians. ● Hand-wired on a universal circuit board. ● 9V batteries cannot be used. ● The aluminum case size is 60 x 112 x 31 (height) mm. The case has not been polished to keep the price down. ● True bypass. ● EBK is a name used only for online sales. In the main business, we adjust, create, and adjust guitar equipment such as amplifiers and effectors specializing in blues-related gear. The number of units produced has exceeded 4000 (as of August 6, 2024), and many professional musicians use them. ● Six-month warranty: We manage customer records, so if a failure occurs during normal use, we will compare it with the shipping records and repair it free of charge within six months. (However, you will be responsible for the shipping costs.) ● Shipping included. ● This is not a copy or clone of Lee Custom products. It is a completely different effector. ● It can also be powered by a 9V adapter. It requires 300mA or more to operate; using a lower-rated adapter or power supply may cause noise or no sound, so please check before purchasing. The polarity is center negative, the same as standard effectors. ● You can check the sound source on Masayoung's vlog #56 on YouTube, so please take a look.