UPDATE: This lock has failed. When using fingerprint, code, and even the key, it simply doesn't unlock. The lock wasn't even being used that much as it is a side-door and not a main entrance/exit. I have to alter the 5 star rating, though it is difficult to decide what rating I should give it. I will have to reduce the star rating to 1 I feel, because a door lock failure is something that should never happen at all let alone this quick, however on closer inspection as in having a closer look inside, it does seem to be poor material choices for the internals, and possibly less than optimal engineering. Outside it looks a million dollars though, and this is where we all often go wrong. Now the dilemma of finding a lock that I can trust, I fear it is time to just go back to good old mechanical locks from established brands such as Yale. ---------------------------------------------------------- First of all, the lock talks to you! A nice modern touch. Secondly, the build quality is solid, very heavy duty and no shaky flaky parts. This is the kind of workmanship one expects from a top quality chinese manufacturer, they who do not cut corners, whence the high price. Sync'd the lock with the phone via the app from the appstore, which communicates with the lock across bluetooth, we registered fingerprints, codes, rfid-tags. The lock uses 4 AAA batteries behind a thick metal cover screwed on with a small black screw. The fingerprint sensor is as good as the ones you have on laptops, fast, accurate and even works fine with slightly wet fingers we found. Now the difficult part is the fitting. As these locks require a fair amount of enthusiastic wood-work, definitely would be far easier on PVC or composite doors. In our case we fitted it on an old-fashioned solid wooden door, took a while but we got there in the end and mighty impressed, as professional as professional comes (even though I say so myself). The lock also has a dead-lock bolt, so if you swing up the handle, it engages the dead-bolt. The handle on the outside can't do anything, until the right code/fingerprint/rfid-tag comes along, and then the lock can be opened and if the dead-bolt is engaged that can also be disengaged. Please note that this lock requires either a very good enthusiastic DIY'er who is not afraid of custom-work to facilitate the installation or a time-proven professional locksmith (beware of the many cowboys out there who blame everything else but themselves for poor workmanship!). Lovely lock, and if the price is dropped a little more then we shall buy a couple more of these without hesitation! PS. Absolutely adore the finish on this lock, well done to the designers!!! This is a great product and proves that Amazon does have real diamonds among a crowd of zirconias, the most difficult task is finding those diamonds, and this is where good honest reviews help. I hope this helps convince you. PSS. I also really do believe this lock is highly efficient with batteries, we took them out after a week, tested them in the charger and the charger came up with 95%!!!!! And that is after a great deal of locking unlocking (new toy and all).