I recently bought the aosu T2 Ultra 4K Security Camera system and to say I have been impressed would be a severe understatement. They work flawlessly with quick responses and amazing image quality and feature set. So I decided to add this aosu doorbell hoping it would be as good as the outdoor cameras are. It is. Picture quality is fantastic and it integrates perfectly into my aosu app. I've tested the response time from pushing the doorbell button to receiving a alert on my phone and it's about 2 seconds! Same with a alert for motion detection. Two way audio works pretty well too. You can speak in your choice of three voices; your own, the "Uncle", or the "Clown". (Yep, seriously) Or have one of three messages played: "Hello, Can I help you?", "Hey there! What are you doing?", or "Please leave the package in front of the door, thank you". You can adjust the sensitivity of how far away you want it to alert to motion and also select if it should do so only if it detects a person. Many, many other features and settings. Another thoughtful addition is a 15 degree angled mounting panel if your door if off to the side somewhat. Really great unit! You will not regret buying this.