Since its release in 1981, the SD-1 Super Overdrive workhorse has been the premier gain pedal for generations of guitarists in every genre of music. The SD-1 is based on the revolutionary asymmetric clipping circuit of the OD-1 Overdrive - one of the three original BOSS compact pedals from 1977. It delivers rich, smooth and highly musical overdrive sounds that continue to inspire guitarists around the world.