Radio Interface Unit (RIU) The Toro® Radio Interface Unit combines the functions of the OSMAC® Base Station and Hand-held Remote Interface (HHRI) in a single unit. Available in a dual radio configuration that performs both Base Station and HHRI functions, a single radio configuration that’s programmable for either function, and a radio-less configuration that’s programmable for either function and utilizes a user-supplied external radio for added flexibility.