Unlike most padlocks, The Bowley 543 lock is virtually unpickable due to its unique design. With its secure locking mechanism, the key must be first inserted and then rotated 180 degrees to the top where the pins live. It then engages them to lock & unlock & this means that picking tools are useless. The shackle of the lock is made of 7/16-inch hardened, nickel-plated steel. It is available in stainless steel, brass and aluminum versions. A funded Kickstarter.