The British Pedal Co. Professional MKII Tone Bender OC81D is a meticulous replica of the 1966 PROFESSIONAL MK II Tone Bender pedals created by Gary Hurst. Unlike the MK 1.5, this model features a 3-transistor circuit, using either OC75 or OC81D transistors depending on production and supply. The OC81D version is known for its warmth and saturation, and it can be heard on many Led Zeppelin tracks, including "Whole Lotta Love." This pedal was also seen being used by Jimmy Page in the documentary "It Might Get Loud".