Thunderbird ‘Classic’ Door Sill Covers – Multiple Cut-Out Style. Our ‘Classic’ stainless steel door sill covers feature multiple cut-outs which provide better adhesion and allow the black ridges of the stock door stills to show through. Constructed of highly polished stainless steel for a brilliant mirror-like appearance, these striking door sill covers also have a cut-out for the stock ‘Thunderbird’ logo. Installs in minutes with no tools. Just peel the backing off the 3M adhesive strips and press into place. Set of two.