SPF (Solartechnik Prufung Forschung) certified. Solar transmission : 91.6% Lmax.: 2130 mm Bmax.: 1830 mm. 3.2 mm/4mm -- low iron, toughened glass. ·SPF (Solartechnik Prüfung Forschung) certified. ·Solar transmission : 91.6% ·Lmax.: 2130 mm. Bmax.: 1830 mm. D: 3.2 mm/4 mm Solar glass