Are you often called upon to play low D or B notes but don't want to switch to a 5 string? You're in good company. That's why the BT2 has been a not so secret weapon of elite bass players since 1982. The ability to instantly drop the tuning of your low string and then back again with the flip of a lever is a great way to keep the gigs coming! The BT2 is a direct replacement for the Schaller® BMF tuner that was first found on CBS era Fender® basses manufactured between 1967 and 1982. Since then, the BMF tuner has been featured on countless boutique builds and Custom Shop models.