This is the SWISCO Series 350 Side-load Channel Balance Sash Support System (also known as a block and tackle balance) for non-tilt windows. The series is determined by the combination of the top and bottom fittings attached to the metal channel. When determining length, only measure the metal channel; do not include the fittings in this measurement.
The metal channel's width is 9/16", but is considered 1/2" in the trade. It houses a spring and pulley system to raise and lower the sash and comes fully assembled with a non-winged 19-002 top guide and a winged 15-004 (1-3/32" deep) bottom shoe.
