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what is the difference between a double and a single cylinder deadbolt?  

What is a "smart-key"?  Does it mean that all the locks come with the same cut key and I then have to change it to make it unique?  I guess they had not been invented when I installed the main locks on the doors (74/75)

Pardon my ignorance :).  I have never run into those terms before.  

Thank you

Hello Hanne,

Double cylinder deadbolts require a key from either side to lock or unlock.
Single cylinder deadbolts require a key from one side have a thumbturn from the other side.

Smart key locks are dumb locks.  They are designed so that the end user, you, can follow a few steps to change the factory key to any other key of the same type, thus eliminating the need to have a locksmith rekey the lock to match another key or to rekey it in case the key is compromised.  These locks are not secure, look at youtube.  They are unreliable.  If you attempt to rekey them as directed and make one false step, you have to see a locksmith or buy a new lock.

Stay away from smart key locks.

Don't use a double cylinder deadbolt unless you keep a key nearby from the inside for emergencies and only if local life safety codes allow the use of one.



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I do not answer Safe or automotive questions. Period. I am knowledgeable in almost every area of Locksmithing. This includes locks, keys, lost keys, residential and commercial lockouts, rekeying, masterkeying, high security locks, access control, electric locks, security cameras and home safety. I have been running an online business since 2004 where I sell all types of lock and security hardware to everyone from apartment renters to business owners to the US government. Before that I started a locksmith service in 1999. I deal with many types of security equipment including high security safe locks, heavy duty padlocks, exit devices, biometric readers, electric strikes, magnetic locks, full surface hinges and I only sell what I personally stand behind 100%. The online business has given me a more in-depth look at the locksmithing industry, helping me to learn more about each and every product that I offer, as well as products I don't have but end up finding for customers to solve any issues they have with security or door hardware.

Please don't submit any automotive or safe questions as these aren't areas that I can help in.


I have been Locksmithing since 1999 and own my own Locksmithing business. I have many years of hands-on experience through the many services I have performed for my customers. I've run my business the way I wanted, treating everyone as I would like to be treated and knowing that any customer could be my last if I didn't perform my locksmithing duties as I had promised.

I have a diploma in Masterkeying, Advanced Locksmithing & Locksmithing from Foley-Belsaw.

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