Mechanical devices and attaching hardware such as locks, hinges, pivots, catches, lifts and pulls, and stays.

 A narrow strip of material placed between window sash or door panels and frame to keep out rain, air, etc. May take many different forms, depending on product design and usage. Welding 

The UD is the precise size of the window (unit) when measured in width and height from the outermost edge of the window frame, not including any installation flange or brick mould. Vinyl-Clad Window

 Invisible rays of the spectrum at its short-wavelength violet end; the invisible solar radiation that can cause heat buildup and fading of wood, fabrics and other surfaces. (Low-E coatings are added to window glazing to moderate or eliminate harmful undesired UV wavelengths of light.) United Inch 

A nearly invisible micro-fine stainless steel mesh insect screen that is one-third the diameter of a standard screen wire and allows over 50% more clarity than an Andersen conventional insect screen. U-Factor

 Also called a transom light, the window located above a door or other window. Triple Glazing

 A term that describes the expansion a material exhibits when exposed to high temperature, or the shrinkage (contraction) that results when exposed to low temperatures. Threshold 

 Double-hung window

 Refers to a physical property that affects the extent to which heat or cold is transferred by a material. For example: aluminum has 1,000 times the thermal conductivity of Fibrex™ material

 An element (space or other material) placed between other elements to reduce conduction. (Andersen uses a vinyl thermal break on patio door