I bought this about 3 years back at our local Wal-Mart, for the reason that we have children in our home and my husband and myself take some prescription medications that could be potentially lethal to others, especially young children.
I got it for around $20.00 and it came with two keys. The interior of the box is 11"W x 71/2" L X 4" D, and it is perfect for storing medications, some jewelery, important papers and such. If you have much more than this you will want to invest in the larger ones.
This box is guaranteed to be fire proof and water proof, but we have been fortunate enough to not to have to test that theory, but I feel pretty confident in Brink's word. Brink's is a company that is synonymous with safety so I really feel good about having papers like marriage certificates, birth certificates, Land Deeds and so on in it.
I think every parent should at least invest in one of these, this is the only sure fire way to make sure your children do not get into anything they are not suppose to.