The storage capacity allows you to store A4 documents and square No. 2 envelopes without folding them. The main body is made of durable steel that will not break even if dropped. You can set your favorite combination of 4 digit lock numbers. You can set your own number from 10,000 different ways. Comes with a snap lock to prevent the top lid from opening or closing if you forget to lock the dial. The included security wire can be attached to a post to prevent it from being carried out.