Designed and manufactured specifically for use in variable-refrigerant flow (VRF) installations, SlimDuct RD-Series and the PD-Series rooftop ducting and support systems can accommodate multiple linesets. The RD-Series comprises 20-gauge, roll-formed, rectangular sheet metal lineset duct and fittings. It features a proprietary, anti-corrosive, scratch-resistant, hot-dipped, and chromium-free ZAM® coating (zinc, aluminum, and magnesium). Widths for the RD-300, RD-450, RD-600, and RD-900 are 12, 18, 24, and 36 inches respectively, and all are 51⁄8 inches high. The PD-Series is designed for smaller installations that do not warrant the larger metal lineset duct. It also serves as a transition to protect the lineset from where it exits the VRF condenser until it enters the RD-Duct. It is made with UV-, fire-, and weather-resistant ivory-colored extruded PVC round duct. The PD-90 has a 3.5-inch diameter, while the PD-120 has a 4.7-inch diameter. Both series can be used vertically or horizontally to protect linesets associated with any a/c, refrigeration, or industrial cooling process equipment. On rooftop systems where the top of the RD-Series duct (Type RWK) has to be used as walkways, a reinforced heavier-gauge cover plate with a nonskid surface is available as a special-order option.