We sometimes install Arlington Siding J-blocks for our outdoor light and receptacle boxes. If the cover is not needed, the base works with all other manufacturer's J-block covers, they nail right over the Arlington bases. The only problem with using the Arlington J-blocks is that they only come in white. I advise that if your facia and trim is white, use our covers, it will look so much nicer. But if the facia and trim is a color, nail your J-block covers right over our Arlington bases and there is no problem in installing the light fixture or receptacle. But remember, to paint plastic items, a plastic primer needs to be applied to the surface before the plastic should be painted. Also, I have experimented with painting plastic with a combination plastic primer/paint and have found that it does not work as well as using a separate plastic primer.