The UL Listed mark provides a higher level of acceptability. KDR Optimized Drive Reactors that are UL Listed or UL Recognized meet the same safety standards but are viewed differently by Underwriters Laboratories. They consider UL Listed products as being complete end-products, versus components that will be used as part of a larger system. While a UL Recognized Reactor may adequately address a system’s needs, the field inspection may require UL Listed products in a given installation. UL Listed Reactors meet a broad range of installation requirements. UL Recognized products may require an addition to a user’s UL file, whereas UL Listed products may not.