The DH-100-P is designed and built to meet all local requirements, as well as the NFPA regulations regarding duct smoke detec- tors. The DH-100-P is provided with a local test button, and output terminals for remote status indicators and test switches. Air sampling is accomplished by two tubes which protrude into the duct. The 7.5" exhaust tube is supplied with the duct smoke detec- tor unit. Once the duct width has been determined the air intake sampling tubes must be ordered. Sampling tubes are supplied in three standard lengths 2.5ft., 5 ft. and 10ft. and cut to size to fit the duct