A set of Lock Bumping Keys can unlock around 90% of the doors in America. Each lock manufacture in essence will have it's own bump key for that lock. For instance, if your door has a Kwikset lock then only a Kwikset bump key will work on that lock. A Kwikset bump key is pictured below.  Another example is if you have a Schlage lock then you will have a specific Schlage bump key made for that lock. So basically there is only one bump key for a brand or model of lock. The manufacturer of these locks don't sell the bump keys They sell the blank keys to locksmiths or companies with a key copying machine under good intentions but the bad guys will modify the key and make a bump key from the blank. This has been going on for awhile but with the advent of the internet and the free transfer of information it is has gotten out that you can make a bump key or basically a modified key that will unlock your brand of lock from a key blank.