This is the waltons 4 x 6 extra tall polycarbonate greenhouse is a great garden building built from durable aluminium frame for more sturdiness and is powder coated in evergreen to offer a more attractive finish the aluminium frame also supports the doors and the glazing to ensure that the greenhouse stays durable over the years to maximise the space in the greenhouse we have installed sliding doors the polycarbonate is a stronger material than glass as it does not shatter as easily the