Em-D-Kay 2491 heavy duty 3 FT long x 10mm (equivalent to 3/8 Thick) square link bicycle maximum strength hardened steel chain. Covered with a heavy weight black cotton sleeve. Sleeve is riveted on both ends to prevent movement and prevent scratching. Welded links for superior pry resistance. Specially designed as a extra heavy duty flexible chain that is extra secure and very tough to break. This lock is ideal and provides security to lock up for a bike/bicycles, outdoor furniture, motorcycles, a ladder/ladders, power tools and other hard-to-lock-up possessions, construction equipment, and many other applications. Fasten around an immovable object such as tree, fence post, bicycle rack, etc. break.