Redback Step Down Collars provide an all-in-one solution for reducing multiple duct flanges. Each step-down section provides a 5 mm tapered flange. Cut anywhere along the flange to ensure a perfect fit every time. Quality ABS virgin plastic is easy to cut and resists cracking. Step Down Collars may be cut into three individual collar sizes, divided and used separately. Step Down Collars stack together tightly, making shipping easy and inexpensive. The affordable, single reducing collar option. 305 mm – 300 mm / 255 mm – 250 mm / 205 mm – 200 mm / 155 mm – 150 mm.