Sterling Silver Medium Curb Chain (3 mm wide x 1 mm thin). 

Sizes:

16" (3 mm x 1 mm) Best for young women, children and babies. 
18" (3 mm x 1 mm) Best for women and young women. 
20" (3 mm x 1 mm) Best for women or young men. 
24" (3 mm x 1 mm) Best for men (usually pulls over head without undoing clasp).  
30" (3 mm x 1 mm) Best for men or women desiring longer length. 

Made in Italy.