Our Engineer Grade Retrofit Label can be applied to one of your existing aluminum signs or can be used alone on any surface too. Stick the label to a clean and dry surface using the adhesive backing to give a facelift to an old, faded or out-of-date sign. 3M Engineer grade sign becomes visible in the dark when light from headlights or flashlights hit the sign face. Printed using 3M MCS (Matched Component System) inks and films designed specifically for traffic and parking signs, the labels comply with DOT rules for parking lots and offer 7 years of outdoor life.