Extreme Heavy Welded Steel 6mm Chain Training Collars for Big Dogs. Ultra-strong, great-quality Chain Collars feature rugged electronically welded steel construction, for the smart training solution that's built to last. High quality Steel. Ultra-strong Rugged electronically welded steel construction High quality Steel Available in 24 inch, 26 inch, 28 inch or 30 inch lengths Additional Details ------------------------------ Product description: Extreme Heavy Welded Steel 6mm Chain Training Collars for Big Dogs. Ultra-strong, great-quality Chain Collars feature rugged electronically welded steel construction, for the smart training solution that's built to last. High quality Steel. Ultra-strong Rugged electronically welded steel construction High quality Steel Available in 24 inch, 26 inch, 28 inch or 30 inch lengths