Window Block and Tackle Sash Balance This non-tilt block and tackle channel balance is constructed of a mill-finished steel U-frame housing. aluminum channel housingCompare old guide ends and note their dimensions to order the new guide endsMust select the top and bottom guide ends that are sold separatelyPrime-Line part H 3740 riveting tool can be ordered separately for installation of guide endsFor further dimensional information, please see the line drawing The internal working components include a spring, cord and pulley system, but the plastic top and bottom guide shoes must be selected separately as they are not included with the balance itself. These window counter balances are used to counter-weight the moving sash on single and double hung vinyl windows. 30 in.