This is the most common type of deadbolt. It consists of a twist knob on the inside and a keyhole on the outside. You have likely seen this configuration on many homes. The ‘dead’ part of deadbolt implies that you need to manually move the bolt using a knob or key. Keep in mind that a glass—paneled door with a deadbolt can still be entered by breaking the glass and operating the knob from the inside.
The broken glass method mentioned above won’t work if you have a double cylinder deadbolt. This deadbolt is the most secure of its kind because it is operated with a key on both sides of the door. This type of lock is sometimes avoided because it makes exiting the home in the event of an emergency difficult. If the deadbolt is locked, you’d need a key to open it. This brings up serious safety concerns, especially in the event of a fire. Some building codes even forbid the installation of these locks, so be sure to do some preliminary research.
The ‘throw’ is the bolt part of a deadbolt. Horizontal and vertical throws offer different types of security. A horizontal throw extends one inch beyond the edge of the door and into the door jamb. This kind of throw can be compromised by an intruder if he can pry the door away from the jamb far enough. Another name for this lock is a rim latch/rim lock.
A surface mounted or vertical deadbolt interlocks with cast metal rings that are attached to the door. The rings make this lock pretty much un-pryable, so a vertical throw is safer than its horizontal counterpart. Some people mistakenly call this lock a rim lock, although it’s not.