Secures in back of neck with hook and loop (velcro-type) closure. SIZING: Neck circumference, SMALL: 10” to 14” (note: very small as compared to like products), MEDIUM: 15” to 17” (most frequently ordered), LARGE: 18” to 20”, EXTRA LARGE: 21" to 23" Minimizes scatter radiation exposure to the thyroid area Patented XPF® Technology contains no lead or heavy metals; non-toxic Provides 0.5mm lead equivalency over the thyroid area and 0.25mm in the remaining areas. Machine washable; can be wiped down for cleanliness Lightweight, flexible, fits comfortably around neck Made in USA Makes a great gift for a graduating medical student Fun patterns: Bones, Camouflage, Hearts, Hops, Jungle Flowers, Rainbow Hearts, Tie Dye, Outer Space, Skulls, Tartan, Tropical Floral, Geometric Neon, USA Stars, Tulips, Scary Skulls. (All fabric options.) See all Thyroid Collars. Visit the BLOXR website.