Usually the main drawback of lever locks is impossibility to change their secrecy (in contrast to cylinder locks where it's enough to change only a cylinder). However, lever locks essentially surpass cylinder ones in other parameters (burglary-resistance, reliability, secrecy).

How to keep protective characteristics of a lock and at the same time to solve the problem of "lost keys"? If you are an optimist (i.e. you do not worry that your lost keys will be found by a thief who knows your address), altruist (i.e. you do not grudge anything for the others) or minimalist (i.e. there is nothing to take in your flat), then just order a new set of the keys and live easy. In other case you need to change the lock (it is rather troublesome, especcially for metal doors). But there is one more way to return your safety to the previous level - to install a transcoded level lock, where it's possible to change the secrecy on your own! It is of current interest for those who has taken out ensurance on property against theft. In this case it is necessary to protect a door against opening by means of key selection or copying a key. If this happens, it is practically impossible to get any compensation  - absence of evidences makes an insurance company suspect the owner of a burglary feigning.

If you use a BORDER lock with a changeable secret block (Nucleo), you will surely protect yourself against these problems. It is especially convenient to install transcoded locks in rooms where there are building and remedial works - it is enough to change a Nucleo after these works. In the originav variant a lock has a technological changeable block with minimal number of secrets and one key, together with the lock a changeable secret block (more than 100 000 secrets) with 5 keys is delivered. Afterwards you can buy only changeable blocks with a set of keys.

Pay attension that the changeable block does not reduce burglary-resistance of a lock. First, it is placed on the inner side of a door and is covered with a special escutcheon. Second, during the closing process the block moves inside the lock case, it is possible to change this block only when the lock is opened.