Bay window: Bay Window is a multi panel window projecting outward from the wall, usually made up of a large center stationary unit and two flanking units and can be assembled almost in any combination.

Balance System: Is the mechanism trough the use of spring, weight to counterbalance the weight of a sash. 

Beveled Exterior: An angled extension from the frame that adds an aesthetically-pleasing dimension to the exterior of the window

Block frame window: It is a non-finned frame that can be used as new or retrofit installation, in a block concrete wall application or when replacing the wood sash of an old double hung wood window.

Bow Window: is a combination of four or more windows that form a round shape, what we call radius. This window is similar to the bay window projecting outward from the wall line.

Bottom Rail: The bottom horizontal member of a window or door.

Butyl: Polyisobutylene is a hot melt sealant used to seals the glass spacer creating an airtight and watertight Insulated unit.