I have ordered and installed 2 of these units, specifically because the buttons have letters too (like a phone keypad), so a code can be a word rather than just a number. This kind of works, although in practice the letters are too small for my old eyes, so it is difficult to read them well enough to enter the desired word. Installation has a few tricks: 1. You are asked to select between right-hand and left-hand based on which side the hinges are on, but of course that depends on which side of the door you are on! They mean when you are on the side of the door which will have the keypad. 2. They don't explain how to adjust the latch backset (between 2 3/8" or 2 3/4"). Turns out there's a little hole, and sticking partially through is a little nubby -- press the nubby in with a screwdriver (or whatever -- it's hard to do), and then the interior mechanism will slide between the 2 sizes. 3. The back mounting plate is not symmetrical, and so will look different depending on which side of the door it is on. This is OK, except that the Step 5 picture shows the notch pointing to the edge of the door regardless of which side of the door it is on, which is wrong, and thus confusing. 4. The battery cover on the second unit was REALLY hard to remove -- much worse than the first unit, which was also somewhat hard. Keep in mind that you may need to make adjustments to the strike plate, etc, so that the deadbolt has an unencumbered entry into its hole. Otherwise it will take 2 hands to lock the door -- one hand to hold the door in the right position for the deadbolt to move properly, and the other hand to push the Lock button. There is one thing I worry about re operation: the knob is quite hard to turn -- just by itself, before even connecting it to the deadbolt mechanism. This means the batteries must work extra hard to lock/unlock the door, thus presumably shortening the lives of the batteries.