This is the High Security Stainless Steel Padlock from Diversi-Tech, part number DT40122. The padlock features a 3/8 inch diameter shackle and, when opened, the shackle leaves a 7/8 inch opening. The outside of the lock is stainless steel and the inner parts of the lock and the shackle are created from chrome plated hardened steel. The inside mechanism is made of brass. To use the lock, a simple notch key is used to open the shackle. You can fit this over your hasp or lock, turn the key and lock it into place. These locks are great for enclosed trailers, toolboxes, or anything else that will fit in a 3/8 diameter shackle. And there you have it for Diversi-Tech High Security Stainless Steel Padlock, part number DT40122. It is also available in a three pack kit, with all three locks keyed alike, and that is part number 40122KA3PK.