The Alloy steel padlock is 25000 pound of tensile strength. Most importantly core of this lock 65 Rockwell core-hardened lock body and shackle. The Shackle diameter is 9/16 inch beside horizontal clearance both is 13/16 inch and vertical clearance is 13/16 inch. The key retaining for added security and cylinder inserted form the top as optimum drill and resistance. The hardened bottom steel plate give additional protection against physical attack.