Glass rooflights can either be Fragile or Non-Fragile depending on the specification of glass used. The most robust Non-Fragile glass is Class 0 and the are used in Walk On Glass skylights fitted in areas which a designed to have foot-fall such as a terrace. Class 1 glass is manufactured to be stood on infrequently for areas where occasional access is required for maintenance, they are not however to be used for every-day foot traffic. Class 2 glass is the most commonly used non-fragile classification, these rooflights are designed to stop a person falling through if they were to trip and fall onto the rooflight. All rooflights have to go through testing to prove they achieve these specific class ratings. Class 3 glass is considered fragile and should only be installed where there is no chance of someone falling through the glass.