Update: I've been selling Pewag square security link chains since August 2016. No question Pewag chains are the best in the world. But after doing some research, I discovered and added a new chain brand to my inventory. The Laclede 3/8" 10mm square link chain. Why did I do this? One reason. It's 'through hardened', which means it's just as hard in the middle as the surface. By contrast Pewag is only 10% 'case hardened'. That means just the surface (still super strong). Laclede is made from quenched and tempered alloy steel. So while Pewag is still an incredible chain, shouldn't Laclede be considered one of the best also? And it's made in America. St. Louis Missouri to be specific. Plus it's lower in price than the Pewag. So hopefully you can check out my Laclede listings. 3/8" (10mm) is every bit an extremely impressive chain. 

Update: I've enclosed a photo showing the 3 different size Pewag Electro-galvinized square link security chains. On the left is the 9/32" (1/4") 7mm, in the middle the 3/8" (10mm), and on the right is the massive 7/16" (12mm), a chain on steroids. 

This listing is for new 4 foot Pewag 3/8" (10mm) square link security chain. Pewag is the best and strongest chain in the world. This chain is perfect for securing motorcycles, bicycles, scooters, gates, and buildings. This chain is case hardened 10%, and is Electro-galvanized for corrosion protection. Square links are superior to round because they do not allow bolt cutters to get a proper grip, and even proves to be a monster against angle grinders ( the heavier 7/16" 12mm chain will resist 'any angle grinder' and 'any bolt cutter'). Of course, with any chain, you need to use a top security padlock. I suggest the SOBO SPSA series D-lock, and Stanley 24/7 padlock. Also whenever possible, keep your chain as high as possible off the ground when locking your property. Thieves with bolt cutters use the ground as leverage when attempting to cut chains.

The surface hardness of this chain is 62HRC, breaking strength is 17,894 pounds, inside link width is 5/8", inside link height is 1.5", outside link width (shortest part) 1 3/8", outside link height (highest part) 2 3/16", and total weight is 8.6 pounds. 

As a small bonus, I will send a 2-3 inch sample of the heavy duty black nylon protective sleeve that fits over 3/8" (10mm) and under chains. It's a great product that protects bicycles, motorcycles, and scooters from any damage. As soon as you see it and touch it, I think you'll agree. I sell a lot of it.