Bump Keys         

Look at the bump key picture below and you will see the difference between your normal house key and a bump key. The bump key as you can see has a distinct look to it. The key is filed down to create little metal spikes which look  like shark teeth on the key. When the l bump key is whacked or hit by the lock bumping hammer it then pushes up all the pins at the same time for a split second. When pressure is applied for this split second all the pins are above the tumbler which enables the tumbler to then turn. The hitting or banging of the key with a lock bumping hammer is where the term "lock bumping" comes from.