"A protective non-scratch hardened D-shackle is a type of lock that is designed to be both durable and gentle on surfaces. It is made from a hardened material that is resistant to tampering and can withstand heavy use without scratching or damaging whatever it is attached to. The D-shackle is shaped like a D and is inserted into the lock to secure it in place. This particular lock also has an easy-set 4 digit combination feature, which means that you can set your own unique combination of numbers to open the lock. The combination can be changed as often as you like, providing an extra level of security. The internal shackle size is 115 x 190mm, and the diameter is 12mm, which is a standard size that is suitable for a wide range of applications. The lock is preset at the factory to open at 0-0-0-0, which means that it can be opened using the default combination when you first receive it."