We recently installed casements in this beautiful Atlantic City, NJ home. This casement window was from our 9000 series and came with a lifetime transferrable warranty. In terms of insulation efficiency, casement windows is good for the tightest seal. When the casement window is closed, all four sides of its sash press firmly. Within a common frame, they are used singly or in pairs, in which case they are hinged on the outside. Casement windows are often held open using a casement stay. Windows hinged at the top are termed to as awning windows, and ones hinged at the bottom are called hoppers.