Vacuum glass consists of two glass panes separated by a microscopic vacuum gap (typically less than 0.5 mm).

• The space between panes is air-free, eliminating heat transfer by convection and gas conduction
  
• Micro spacers (support pillars) are placed between panes to prevent collapse under atmospheric pressure
  
• The edges are hermetically sealed, maintaining a permanent vacuum
  
• Overall construction is extremely slim, often close to the thickness of single glazing
  

Structural takeaway:
A thinner, lighter unit with a highly engineered internal structure designed for maximum insulation in minimal space.