These are stand-alone mechanical locks that need
no batteries. They
come basically two ways: Extremely heavy-duty (battle-ship) and medium-duty. Usually, they can be installed in place of regular locks
with only minor door modification. They are great for people
who don't like to use keys! They only work with one code as opposed to electronic locks that have the ability to use more than one code - sometimes many codes.
Please keep this in mind: Because these are mechanical,
with no power assist from an electrical source, they are not generally suitable for some disabled people or those with
weak hands. These people should check out the electronic locks
or some of the other technologies such as
chip reader system
or
proximity reader system. but if you need a keyless lock to last a long time (generally speaking) or if you will be using your lock outside or near the ocean, a mechanical keyless lock will usually hold up much better that an electronic lock.
No battery needed for these locks!