9mm four-sided chain links made from triple heat-treated boron manganese steel The chain secures with a new patent-pending Integrated Krypto Lok series 2 Lock head with talon deadbolt The innovative chains also include a new patent-pending pin-less link design which allows for no weak link in the chain Chains are enclosed in a nylon-webbing sleeve to protect paint from scratches & allow for compact coiling while transporting Recommended for use in low to moderate crime areas. The new 'I' key makes opening a disc-style cylinder much smoother Approved to Silver Sold Secure standard