Retro-Fit Boards provide the perfect solution for replacing or updating old boards. . . Without removing them. This innovative board is made with 28 gauge porcelain steel surface mounted to 1/4" rigid board with a Mylar backer. It can be installed in minutes--over both wood or aluminum-framed boards. Factory-drilled, counter-sunk holes in the board frame enable you to hang new board quickly and effortlessly. Porcelain steel surface is backed by 50-year warranty. All Retro-Fit boards are built to order and non-returnable. MARSH ORDERS TOTALING OVER $1000.00 SHIP FREE.