A few years later, Ardeshir patented the first of his inventions, a lock that would subsequently be called a "Gordian Lock". It came with two keys, both of which could lock and unlock the device, but the second key could also be used to modify the inner workings of the lock and so render the first key useless. Shortly thereafter, Ardeshir developed a lock based on Jeremiah Chubb's 1818 "Detector Lock" design, which, as the name suggests, made the owner aware of attempts to use an incorrect key. When one attempted to do so, a bolt was thrown that could only be released with the correct key, and only if the key was first turned as if to unlock the lock. Like Charles Chubb's patent of 1824, the Godrej lock didn't need a special "regulator" key to restore functionality. In a small booklet that Ardeshir published and often distributed himself, he claimed "the work is done on modern methods, with the aid of modern machinery with which the factory is equipped throughout at a very large outlay. We do not buy our locks or any safe parts ready-made, but we manufacture all our requirements ourselves. We have a large number of specially trained lock-makers having over 15 years of practice. This enables us to make our locks as accurately as those by the best European makers. Our keys are all deep-forged and machine-cut and not filed out by hand. We cut the keys first and make the locks to fit the keys. This makes our locks absolutely unpickable and ensures long wear."