The Crime Prevention Website

I just received the following message from Fred Brown asking me for some advice and I thought it would be useful to publish my reply.

Here’s Fred’s message:

Dear Crime Prevention Website

Hi, a great site, read all of it. I wonder what you think about the Viper lock as seen on this link

I'm worried about my parents' security after a number of nighttime break-ins nearby. I would be very grateful for a comment and advice. Thanks, Fred

Here’s my reply:

Hi Fred

Re your enquiry about the viper lock.  I've taken a look at it and watched the You Tube video and I have these points to make.  By the way, you don't mention which country you reside in, so please note that my reference to BS 3621 below is for a British audience. 


  • Useful for a little extra security to support a conventional mortice and or rim lock on an inward opening timber door
  • Useful as a child lock if set at a high level to prevent a toddler letting themselves out of inward opening front/side/back doors
  • The screw fittings are at 90 degrees to any force that might be applied from the outside - this is good, but using longer fixing screws might be useful in this respect
  • Easy to fit
  • Does not prevent emergency escape in a fire as there is no key to find
  • You can see at a glance that they are on or off quite easily


  • This product is better described as a door bolt insomuch that a 'lock' usually has a key and this thing doesn't.
  • As the product does not use a key then it can be undone from inside and would not conform with insurance requirements for a conventional house/bungalow - if used as the sole method to secure the door.
  • Claims of being 12 times stronger than a conventional 'deadbolt' are not supported by evidence that can be verified - at least I couldn't find any!
  • The device does not meet BS 3621, which is the minimum standard for a door lock accepted by the insurance industry and therefore should only be used to support an existing BS lock. 
  • Although the product would fit most inward opening doors it may not be suitable for those where there is a large gap between the door and the frame
  • Because it is fitted on the inside and cannot be undone from the outside the device may not be suitable for use on a door where it may be necessary to affect an entry in an emergency - e.g. an elderly person who may need assistance


  • I have no doubt that this door bolt will have its uses, particularly for child safety, and will contribute a little extra security for a conventional timber door locked in a conventional way - mortice deadlock one third up from the bottom and a rim night latch fitted one third down from the top.  It's clearly a lock for use when you are at home and I can see them being used in multi-occupancy flats in converted houses where the landlord locks often leave a lot to be desired.  I don't see much benefit in fitting it to an enhanced secure PAS 24 2016 doorset that already has multi-point locking.   
  • I presume your parents have timber doorsets and so they would be useful as a little extra security at night and can be easily applied during their nightly locking up routine.
  • Please carry out a free and confidential Home Security Survey of your parents' home using my application.  This will reveal what can be done to improve your parents' home security.
  • Please check out my nightly locking up routine and advise your parents to follow it to the letter


Please acknowledge receipt of this email.  I will be publishing my reply to you on my news page (with name changes) for the benefit of my other readers.  Thank you for bringing this product to my attention.

Please note that I have given you this advice in good faith and without contract. I have not physically seen or tested the product and so you should not accept my comments verbatim - they may be wrong!  

Best regards


I’m often asked for my views about new security products and I’m always happy to respond.  In most cases I steer the enquirer towards my home security survey and other relevant pages to make sure that they have understood the basic security requirements first, before spending money on something that may make little difference.

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