The ACK1 is a universal accessory caster kit used for transportation of compatible JBL products. The kit includes four tour grade casters and the hardware necessary for attachment to the cabinet. The housing and wheels are black for a discreet look even in situations where the rear of the product is facing the audience, as in cardioid Subwoofer stacks. Each caster has a load rating of 100 kg (220 lbs), and the wheels are made out black polyurethane. For more information on how to attach the ACK1 refer to the product’s Rigging and User Manuals.