About this product
One of the longest standing locks on the market and originally released in 1971 under the model name Impregnable. They are still made today using the same 'old school' high quality manufacturing techniques. Expensive yes, but reassuringly so.
Ingersoll used to be a family owned British company but since acquired. They continue to make a small but highly regarded range of padlocks which are still manufactured in England. This is unconfirmed but our suspicion is that they were originally made for Military contract and no found their way into the civilian market as a high security padlock.
NATO stock number (NSN): 5340997662572
This is the most secure of the Impregnable Range by Ingersoll. It is basically a closed shackle padlock but with extra high walls which leave a tiny gap for the shackle which is not clearly shown by the picutre. It will slot directly onto a latch and then make it nearly impossible to remove without the key.
In order to fit this lock you basically have to design your latch or hasp around it rather than buying a lock to fit. It may sound crazy but a lot of people, including Nato have done exactly that.
It is made from hardened steel which is graded in the UK and then finished in a dull nickel chrome plate to give it some weather resistance. This is important since imported steel from China can be of dubious quality. Strangely, the mechanism uses levers rather than disc or pins which have, in recent times, been seen as less secure. That said this lock used 10 levers which is twice the number required by UK insurance companies for lever padlocks. Can it be picked? Highly unlikely.
Body and shackle are hardened so forget about cutting it. Drilling? Well as you can see from the image below there is a Z shaped anti drill bar preventing that and then a keyway cover that slides over the top.
3 keys with every lock as standard. Note that you will not be able to easily get new copies made since the key blanks are not commonly stocked by high street locksmiths.
Interesting articles showing the release of the Impregnable Series back in 1971. Still the same high quality today.
Lever cylinder non aligned in locked state
Shackle is completely removable from this version