Thunderbolt Alarm Padlock with a siren has a built-in sensor that can detect movement to activate a 110dB alarm sound to ward off thieves—built with a heavy-duty, corrosion-resistant body and a thick stainless steel shackle for increased strength and high security. The Padlock is weatherproof, has a dual high collar body to fend off bolt cutter access, and includes three (3) high-security keys. The Thunderbolt Padlock can be used with the alarm sound or on the silent mode by simply reversing the shackle. It is straightforward to operate as the alarm resets automatically and includes two (2) sets of batteries. A Thunderbolt label is applied to the lock body to warn potential thieves there is a siren alarm built into the lock, and a break-in attempt is not advised. This lock is perfect for securing box truck roll-up doors, trailers, bikes, motorcycles, construction equipment, buildings, and any other application that requires a padlock. Two size hasps are included for more options in fitting on different size truck handles. See the photo with size details. The padlock's high collars are meant to deter bolt cutter and sometimes will not fit on some latches because the hasp open area is too small, however, the collars can be grinded down for a custom fit if needed.