J4 - 8mm x 1200mm. The Stronghold range of Squire chains are made from hardened steel and offer very high security. Stronghold chains are ideal for locking perimeter gates, substations, heavy goods vehicles, etc. This chain would be recommended where there is an increased health & safety risk to the public or employees.. Sold Secure Approved. High Security. Hardened Alloy Steel. Durable Sleeve