Currently one of the most popular choices, block and tackle window balance systems include a combination of two or more pulleys, a cord and a spring. The pulleys are grouped as the “block” to reduce the load the homeowner feels. In addition, as the cord (or “tackle”) is pulled by the movement of the sash it stretches or compresses the springs, which are weighted to match the sash weight. The pulleys and springs assist with opening and closing the window. Browse block and tackle window balances, parts, and accessories.