Various Sizes in Stock. Financing with Zero Interest. Warranty period of 20 Years. An in-demand item, the 6’x6′ Leopard Tongue and Groove Windowless Apex timber shed is a top choice among customers. This variant of the popular shed does not include any windows, which can be ideal for individuals looking for a private and secure storage solution without compromising on quality. The 6’x6′ Leopard Tongue and Groove Windowless Apex Shed.