Our 9" Round Stiff Poly Chimney Brush is designed for insulated metal chimneys and stainless steel or metal stove pipes where manufacturers recommend not scratching the flue. These sturdy plastic brushes will help prevent damage to older or more fragile chimneys. The spindle has a 3/4" loop on one end and 3/8" MaleNPT Thread on the other.The 5SB-36048M 3/8" NPT brush rods will mate to the threads on this brush. You can also use the5SB-30624M brush rods and a5SB-36352M 1/4" NPT x 3/8" NPT adapter.Note: If going thru a 45 degree or more elbow, use ProFlex Rods and a female to female adaptor.