GE Security 505 521 Series CleanMe Interpreter & 2 to 4-Wire Converter, Serves as an interface between the 521 Series smoke detector and most 24 V UL listed control panels, interpreting the CleanMe signal. Allows a central station to be notified when a detector needs to be cleaned. Converts any ESL 2-wire smoke to 4-wire inputs. 3 diagnostic LEDs. 12 - 33 VDC. UL, CSFM, MEA listings.