BaronLFI Black Coated Screw Caps with Theft Deterrent Screws for License Plate Frame Snap Caps are black coated and will not rust. Fits #10, #12 and 1/4 - 20 screws The combination of the pin, located in the middle of the allen screw, and the special Allen key makes it impossible to remove the screws with a typical allen wrench or screw driver.