Standard 12U Mixer Cart for Marching Band - by Corps DesignCorps Design Mixer Carts are engineered for maximum equipment protection and durability in the field. The first layer of protection comes from our foam filled no flat casters, designed to absorb vibration and eliminate downtime from flat tires. The second layer is our exclusive shock mounted rack system, featuring both front and rear rack rails suspended on rubber bushings to help dissipate the shock and vibration of normal transportation. Each mixer