BPP-6 Boston pitch pipe for guitar BPP-CC Boston chromatic pitch pipe BTU-150 Boston chromatic clip tuner BTU-200 Boston chromatic clip tuner (also G+B+U+V) BTU-205 Boston chromatic clip tuner (also G+B+U+V) BTUM-3 Boston clip on tuner pick-up IT-5 Boston Intune Series chromatic clip tuner