I received the E330 smart lock today and was very excited. It is still in its original packing and I have been waiting to install the door lock during the weekend and thought of going through some reviews. Just for the sack of comparison, I compared E330 with other models ( S330, S230, C220 and C210). All the features look great, and I saw some extra features with E330 for its price tag but I was not too impressed by lack of two main features: lack of Door Sensor and SD Card ( it does have only 8GB eMMC storage ). The lack of chime and SD card, of course has been mentioned but the lack of door sensor is not clearly visible on the E330 product page. Even a lower priced product S230 seem to carry door sensor. I was bit of disappointed with the E330's lack of a door sensor, which prevented the door from disengaging the auto lock when it was wide open. Myself or my wife would often go out to errands like throwing garbage/recycle stuff to the back yard using the front door and also to bring letters from the post box located at the curve, few hundred meters away. Being senior (65+) we may forget to close the main door behind. The auto lock would engage on the door bolt engaged while leaving the door wide open. There is a count down timer that relocks itself but it would not be very helpful in the above scenario. This makes me nervous, and this is the reason that I might consider returning the Smart door bolt.