Native Treasure 18" Dark Chips Puka Shell Jewelry Necklace Standard 18" Length. Should fit up to a Size 16.5" Shirt Collar Size 9-12 mm 'Good Karma' Super Class 'A' Quality Medium Size Real Natural Shells - No Paint Added Hand-Crafted in Our Tropical Jewelry Shop by Our Native Island Artisans Includes FREE Stainless Steel Beading Wire Upgrade, Sturdy Twist-Barrel Lock Exclusive 60 Day Free Breakage Replacement 100% Satisfaction Guarantee