This block and tackle balance is used on Hurd Energy Saver Concealed Jamb Liner Double Hung / Single Hung and H3 Lines.
Also used on other manufacturers windows - customer will have identify and match up picture.
To order block and tackle balance: See number stamped on side of metal and match it up to the options.
Due to the multiple sizes available these are not a stock item and have a 3 week lead time. Special order item NO returns.
You will receive once balance system. if you need to replace both the left and right side on one window order QTY 2.