KaShDa Gunmetal Plated 4MM Curb Chain Necklace Extender 12MM Lobster Claw Clasp 1" - 12"- Nickel Free Adjustable length extender your choice of lengths from 1" to 12" including the clasp. 4MM (+/- .2MM) Gunmetal Plated Brass Core Curb Chain with links that will accept clasps up to 3MM wide 12MM (1/2") Gunmetal Plated Brass Core Superior Quality Lobster Claw Clasps. Easy to move from one piece of jewelry to another. For jewelry pieces weighing up to 15 ounces.