Automatic Mini A320 Vacuum Robot, Amtidy Robot Vacuum Cleaners (Silver) Smart 4-in-1 Cleaning design - Sweep, Vacuum, Dry Mopping and Sanitize Extremely low noise &lt; 50dB - Unique & precise mould design and compact structures make noise level lower than other robots in the market; Anti-collision - When moving closer to an obstacle, it will either slow down for soft bumping, or completely avoid the object; Cliff sensor - Cliff sensor detects stairs to avoid falling down; Automatically Recharge - The cleaner will automatically find charging docking station when in low power, after full charge, it will go on working;