Spandrel panels are the opaque parts of a curtain wall where the glazing material is necessary to conceal insulation, floor slab edges, ceiling features, HVAC equipment, and so on. The spandrel glazing is normally needed to look like the glazed vision area from the outside of the structure. Spandrels can also be called header panels because they span the distance between the structural members of a building. As with any other type of glass, spandrel glass has two main benefits: it allows light to enter the building while providing visual appeal and protection for people inside the building. However, due to its opaque nature, it prevents anyone outside the building from see into the building unless a window is open or a person walks right up to the glass. This feature provides added security for buildings with valuable or sensitive contents. There are several types of spandrel glass, including insulated glass, translucent glass, and transparent glass. Insulated glass consists of two panes of glass that are separated by a layer of air or some other gas such as nitrogen. This type of glass does not allow any visible light to pass through it and is used in energy-efficient windows. Translucent glass is similar to insulating glass except that it allows some light to pass through it. This type of glass is used when visual appeal is important but privacy is not necessary. Transparent glass can be either clear or colored and is used when full transparency is desired.