Remember when we had to use a physical key to both unlock our car door and start the engine? How inconvenient now that we can leave our keys in our pocket and just open to door and push to start the engine? Someone smarter than me figured out that we can use similar technology to sync our smartphones with smart locks to open and lock doors. The two best products on the market are the Kwikset Touch-to-Open™ Kevo smart lock and August smart lock.