The GB-10 is a useful tool for guitar and bass players to learn, play along with, and record new music using headphones. Copy song files you wish to practice from your computer and play your instrument while playing the file. You can adjust your instrument volume into the mix. Features: -Variable speed function that allows you to change the playback speed without changing the key/pitch -Loop function to let you isolate a particular section and hear it over and over. -Change the pitch of the music so that you don't need to re-tune to play something that is, for example, a whole step down. -Also included is a tuner, metronome, and several built-in effects In addition, the performance of any connected guitar or bass can be recorded with or without the music files. Includes 8gb SD card and USB cable. Uses 2 AA batteries, or 5V adapter (not included) Here's a link to the Tascam site for more specs and info: https://tascam.com/us/product/gb-10?srsltid=AfmBOoqPZiVzhmLWwXkbKM8A-JMmaaB5XAvcaTIkmnwfndx-WVo7xPTz