Directed Electronics RFLUB Universal RF Loop UNIVERSAL RF LOOP Transponder not included Compatible with DLPK RF loops from Xpresskit are an all new line of preloaded RF transponder rings that can be plugged into the DLPK module and allow it to operate as a combo door lock and transponder bypass solution with one single module. Universal &nbsp;RF transponder ring compatible with: Optimax series DLPK module&nbsp; (requires a preprogrammed transponder pellet)