Heidi Swapp Lightbox Alphabet Inserts - Serif Teal. Create clever signs with teal Lightbox alphas. Simply arrange letters for a fun look to parties, weddings and home decor. The possibilities are endless! This 3 1/2 x 3 3/8 x 1 1/4 inch package contains fifty lightbox inserts. 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.