The Double Crusher is our answer to the Question; How can we get more? Our solution four 20mm sensors dedicating two for each side of the bridge. Its the only upright bass pickup of its kind and was designed in September 2020. Each unit is handcrafted to order in Milwaukee, WI. These are a complicated build so they are limited and we will pull them off the market if we have too many requests. We recommend professional installation as the sensors can not be adjusted like our other models. They tend to be thicker just due to the construction.