Series 25 Thermal Break Aluminum Single Hung Window FEATURES Main Frame: Deep sill baffle with bottom sash interlock and weatherstrip—assures complete weather-tightness.  Wide interior frame design for ease of returning interior trim to frame. Weather stripping: Combination of polyethylene weather-barrier fin poly pile and bulb vinyl to eliminate infiltration of air, moisture and dust. Balances: Removable top and bottom sash—bottom sash operates an Block and Tackle sash balances. Glazing: Glazed with wrap around vinyl for weather-tightness and neat appearance. Full 3/4” thick insulating glass. Low-E glass available. (Colonial Light Design has divider bar sealed inside the insulated glass unit.) Lock: Spring loaded, self-locking latch tightly secures moving sash. OPTIONS Low-E glass available in "High Performance” that delivers maximum thermal and solar heat gain performance or “Standard” Low-E for increased thermal performance at a more economical price. Bronze or gray tint, obscured and all glass options listed are available in tempered. Available Finishes: Bronze, White, Driftwood. 3/4" internal grids.