The Obsidian lock is sleek, modern, key-free, and “smart” and can be had in a stand-alone touchscreen model ($180) or connected to Z-Wave-enabled security and home-automation systems ($230). Homeowners can control the smart lock via a smartphone app or the touchscreen. When the lock is connected, locking or unlocking the door can trigger reactions from other connected devices, such as the lights or thermostat. For security, the lock prompts users to touch two random numbers before entering their code, so that they leave fingerprints across the whole screen rather than on the same four digits.