This Master Sweep chimney brush head features a shape 6 inch x 6 inch square, It features a swaged 3/8-inch thread fitting NPT-type thread, The brush head is made of tough, durable flat wire bristles, The bristles are used to score the glazed on creosote before using the creosote removal solution, These flat wire brushes are made for top-down sweeping, This brush head won"t spring back to its original shape if it is jammed past the damper, Master Sweep chimney brush head with a 6-inch x 6-inch square shape, Features a plated, double swaged 3/8-inch thread fitting of the traditional-course NPT-type thread, Tough, durable flat wire bristles are used to score glazed creosote before applying a creosote removal solution (purchased separately), Master Sweep flat wire brushes are made for top-down sweeping from the roof, Brush head won"t spring back to its original shape if it is jammed past a damper frame, Brush head has a has a heavy-duty double spiral 0, 177 dia, spindle design, The seven inches of fill is two on two high density oil tempered 22 gauge 0, 0286-inch wire bristles, creating uniform rugged bristle distribution, Master Sweep brush heads are long-lasting professional brushes that withstand the demanding abuse encountered by busy commercial chimney sweeps, Cleans chimneys more thoroughly and outlasts many comparably priced brush heads, SKU: RTLD178