Although most of our United States Navy Medical/Dental Patches have an iron-on backing, we recommend that you sew them on for longer lasting results. Our Patches are made from colorfast threads on heavy backing to keep their shape and good looks. One of these Patches is a great way to identify the Medical/Dental specialty and training that you or someone you know worked so hard to achieve in the Navy. These Patches measure approximately 4 inches. Your satisfaction is guaranteed, period. Usually ships within 4 - 7 business days.