The Master Lock No. 4401DLH Bluetooth padlock features a 2-7/32 in (56 mm) wide metal body for durability. The 11/32 in (9 mm) diameter shackle offers 2 in (51 mm) vertical clearance and is made of boron alloy, offering maximum resistance to cutting and sawing. The smartphone/app interface offers speed, ease of use, & greater control with the ability to share access, with keyless convenience. The locking mechanism features anti-shim technology, offering maximum security. The 1 Year limited warranty provides peace of mind from a brand you can trust.