The Pros & Cons of Combination Locks

Keys

• One major benefit of using combination locks is that they don't require keys, which can become lost, damaged or stolen, or even locked inside the area the lock is securing. While someone could find the combination written on a note, it's possible to take measures against this (such as by hiding half of the number in one place and the rest in another location). If you do want to have a key just in case someone loses the number, consider buying a combination lock that includes a backup key.

Control

• Some high-end, sophisticated combination locks provide adequate security to protect the vaults in banks, according to the Encarta Encyclopedia. Banks can set them to only open during certain times of the day, which makes it even more difficult for criminals to access the vault during hours when fewer security personnel are present.

Inconvenience and Lack of Security

• It takes a bit longer to open a combination lock than a key-based lock, and it is possible to forget the combination number and leave the written number inside the locked area. An intruder could potentially open the lock by guessing different combinations; although this would take time, it's best not to use combination locks in secluded areas. The King County Sheriff's office advises against using combination locks to secure a home, calling their protection level "very poor."

Installation

• Combination locks cannot be locked from the inside and outside without installing two separate locks. It may be more convenient to use a door with a knob that features a key hole on one side and a locking mechanism on the other. Also, before you can add a combination lock, you must install two strong metal brackets that line up properly. Some storage compartments have built-in combination locks or holes for installing them, which makes installation much easier.