@Linda1197 we've been using it for a year and are pretty happy with it. It automatically generates the codes, triggered by new reservations, and automatically emails each Airbnb guest their code. The locks do not require WiFi, which was important to us. The negatives have been:
Installing locksmith was not impressed with quality of lock.
We had to send one back as it didn't work and the replacement sent was the wrong color; customer service was sloppy and only available during regular business hours.
There is no way to cancel or modify a code once it is delivered to the guest. (Of course, the guest doesn't need to know that.) So guest cancellations and early check-in or late check-out require some management.
The emails it generates seem to end up in guests' spam folders more often than not, so we always send a copy within the Airbnb system.