The disclosure includes multi-layered panels (10, 60, 204) including exterior layers of glass (12, 44) and interior layers of urethane (20, 36) and at least one layer of polycarbonate (16) between the urethane layers (20, 36) that result in enhanced shatter resistance within panels (10, 60, 204) that weigh between about 4.1 and 4.6 pounds per square foot. The panels (10, 60, 204) include an insertion tab (23, 61, 23) of the polycarbonate layer (16) that enhances performance of the panel (10). Reinforced passageways (70, 200, 300) such as doors and windows of schools, hospitals and other public and private buildings, are disclosed using the multi-layered panel (10, 60, 204) with the insertion tab (23, 61, 23).

A spacer, window assembly, method of manufacturing a window assembly, and method of manufacturing a spacer is described herein involving window assemblies having three sheets of material, which will be referred to as a triple pane assembly. Two interior spaces are defined within the window assembly: a first air space between the first sheet and intermediary sheet and a second air space between the second sheet and the intermediary sheet.