Flat steel bristles for maximum cleaning of sand, grit and light obstructions from duct | Pulling eye on one end and smaller twisted eye on the other end for tailing line allows bi-directional use | Can be pulled to loosen dried material before using mandrels or spreader swabs | For use in 6-Inch ductsAmazon.ca Product Description BRUSH-WIRE 6" (39286) From the Manufacturer Greenlee wire duct brushes have flat steel bristles for maximum cleaning of sand, grit and light obstructions from duct. Pulling eye on one end and smaller twisted eye on the other end for tailing.