Anyone wishing to color-key the Challenger engraving on their door sills can now do so by applying a decal. See: Dodge Challenger Door Sill Plate Guard Overlay Decal | eBay
From what I understand, the letters just drop in. It applies just like decals for your car. At first I thought it was just one piece of clear vinyl, but I don't think so.
They are a cheap way of dressing up the door sill. I like the look and all the colors match our cars.