From Fender:

"

From single-coil to humbucking pickups the output varies, potentially causing a nightmare when it comes to dialing in your tone with multiple guitars through the same rig. If you're using one guitar through a complex pedalboard, your signal strength can also suffer due to cable capacitance. Enter the Level Set Buffer, a brilliant buffer pedal that lets you easily swap guitars without negatively affecting your tone. This original design features Level, Hi-Freq and Load controls to adjust the signal, along with a Main Mute footswitch for silent tuning. The tuner output lets your tuner be always on without interrupting your signal path."

Brand new.