Heidi Swapp-Lightbox Word Strips: Heart. The perfect addition to the Heidi Swapp Battery Operated Lightbox (sold separately). Design custom signs for parties, evens and home decor! This package contains three 3x12-1/2 inch word strips in three designs. WARNING: This product contains chemicals known to the State of California to cause cancer, birth defects or other reproductive harm. Do not mouth or chew. Imported.