All Categories > Window Weatherstrips > Window Weatherstrip - Double Hung Windows - Series No. 35 - Unique Balance Type      Printable Page     Email This Page     Save To Favorites Window Weatherstrip - Double Hung Windows - Series No. 35 - Unique Balance Type Designed especially for use with Unique Balance Sash. Features: the interlocking strip offers weather tight construction without interfering with the operation of the balance. It also allows for expansion and contraction of the sash. How to Specify: all double hung windows shall be equipped with Unique Sash Balances shall be equipped with Series No. 35 equipment, all zinc (or cold rolled bronze) in accordance with manufacturer’s standards