In multi-story buildings the sections between floors, where building components are held, is called spandrel. When a building has a full glass facade with a seamless appearance, the glass covering the spandrel areas is referred to as spandrel glass. Spandrel glass has both interior and exterior applications, though spandrel glass used on the exterior of a building usually is heat treated and insulated, to ensure it provides the properties similar to that which an actual wall would provide. Interior spandrel glass does not need to meet the same criteria. Spandrel glass often is also reflective, which helps it to mask the space behind it.