Protector lock

[2] Hobbs claimed that his design was impossible to defeat and superior to the locks that were then in use, but, in 1854, one of Chubb's locksmiths was able to crack it with the help of special tools.

Kromer's lock was designed for mass production and was highly successful, rapidly outselling Bramah's.

It was produced for more than 125 years with many further patented developments,[5][6] and is regarded as one of the most secure locks ever made, remaining without a public demonstration of picking until October 2022.

The lock was not only hard to pick; it was also difficult to tell what shape the key should have by mere inspection inside the key-hole.

Since the lock could be fitted to anything from a small strong-box to a huge bank vault, the keys were made in corresponding lengths, including foldable keys with sufficient length to pass through a thick vault door.