Outdoor wood letters are made from MDO, or medium density overlay. This material comes with a paper face which includes specific water proof resins to help your letters weather the elements. These outdoor wood letters will require proper painting, and sealing to keep the moisture from delaminating the plys of the wood. We recommend a heavy primary, and a good quality outdoor paint. Oil based is best, but acrylic will work as well. These letters will last several years. For a more permanent solution consider HDU letters.