R1 – A double glazed unit with acoustic ratings. Glass construction from outside to inside is 6H-Tg12Kr-33.2SiT. The outer pane is a 6mm toughened glass and a 12mm warm TGI spacer filled with inert krypton gas. The 6.8mm internal pane is an anti-burglary class of laminate 33.2 (class P2A, EN 356,1(B)1 wg EN 12600), complete with a low emission coating and a sound proof film. This glazing unit produces a U-Value of 1.3W/m²K.