These sash pulleys are the finest available in appearance, durability and function. Model PBB 250 pulleys are designed for large, heavy sash weights up to 2-14 diameter such are found in commercial and public buildings. Residential and smaller buildings typically require the smaller 2-14 pulley, click here for more information.The pulley is carefully designed with a precisely machined faceplate. The radiused ends allow for rapid, simple and accurate mortising with a standard 1-18 diameter router bit. Housing body = 2-78 X 78 X 1-78 deep. The solid brass forged and machined housing shields the ball bearing and axle, preventing dirt and grit from affecting performance and assures many decades of easy operation. The wheel is CNC machined from solid brass. The pulley utilizes a chromed steel axle and sealed ball bearing and is available in five finishes: Lacquered Brass, Unlacquered Brass, Oil Rubbed Bronze, Polished Nickel and Satin Nickel. Use of bronze or stainless steel sash chain with these pulleys virtually eliminates all maintenance to the weight and pulley system. The pulley accommodates a full range of sash chain, however the use of the larger #35 and #45 chain is strongly recommended for use with heavier or sash with insulated glass.