British Pedal Company Tone Bender Professional MKII OC81DBritish Pedal Company Tone Bender Professional MKII OC81D The BPC MKII Tone Bender OC81D is a detailed replica of the 1966 PROFESSIONAL MK II Tone Bender pedals created by Gary Hurst. The circuit unlike the MK 1. 5 had a 3 Transistor circuit which, based on production supply comprised of either OC75s or OC81D transistors. This OC81D Loaded MK II can be heard on many Jimmy Led Zeppelin Tracks such as Whole lotta love. This was the pedal seen being used