imported nylon,wear-resistant,flexible,suitable for condenser tubes cleaning, diameter can be 1/4~1", metric M6 brush ... FOR CONDENSER, CHILLER, COOLING TOWER, EVAPORATOR, ABSORPTION MACHINE, HEAT-EXCHANGER TUBES CLEANINGSpecifications:Available for tube sizes 1/4"-1" Cleaning Diameter ... .60.8822.20.9423.81.0025.4 Nylon Tube Brush (round cleaning brush,copper tube brush,chiller brush)