This is a Plain 20 inch 1 mm Box Chain Necklace medium thin and Very Strong and wont get caught in hairs Box Chain is a link chain made with flat wire its Square Shape Light weight but a Very Strong Unisex Silver Chain Comes with Lobster lock for extra security Made in Italy Solid Sterling Silver Nickel Free Chain This Thin Box Chain is the most popular type of pendant chain. It is Solid 925 Sterling Silver Italian Made and It Is about 1/32 inch (1.0 mm) Thick. Strong and flexible. as in all our chains it is NICKEL FREE Silver.