The glazing on this greenhouse is 1mm thick clear polycarbonate, which is 200 times stronger than Horticultural Glass because it is not rigid and therefore is not brittle. It lets in more light than glass and cuts out more than 99% of harmful solar UV rays. This is probably the safest glazing available. This greenhouse is simple to construct using the comprehensive instructions, and will give you many years fruitful use. The framework is guaranteed against corrosion for 10 years. The Ridge Height is 6'8" and the Height on the sides (Eaves) is 4'4". PLEASE NOTE THE PHOTO SHOWS AN 8FT LONG MODEL. THIS 4FT MODEL HAS THE SAME FRONT WITH A DOOR IN THE 6FT SIDE, AND HAS 2 BAYS OF GLAZING DOWN THE SIDES, INSTEAD OF THE 4 SHOWN IN THE PHOTO.