The Roomba was unveiled in the year 2002, and is manufactured and sold by iRobot. There are three generations to the Roomba. The model called 'Roomba' was the only first generation vacuum launched, and was improved upon in 2003. The Roomba Sage is one of the third generation Roomba vacuum cleaners. The approximate size of the Roomba Sage is a 9 cm high and 34cm wide disc. An infrared sensing tool is set up on the front half of the Roomba. It is also fitted with a carrying handle on the top of the unit. The third generation Roomba cleaners have been programmed to detect the size of a room by calculating its dimensions. The Roomba Sage comes equipped with an APS fast charger that is capable of charging the Roomba in just three hours. It also has a wall mount that stores the Roomba Sage conveniently off the floor. The Roomba can detect the homebase by using the infrared tool to recharge the battery. The Roomba Sage has three cleaning modes 'clean', 'max', and 'spot' that help the robot clean specific areas accurately. iRobot has included dirt detection, stair avoidance system, surface transitioning, and bag-less debris bin features into the Roomba Sage. It has a long-lasting battery life that lets the robot clean non-stop for two hours. The dual virtual wall unit uses the Roomba Red's infrared feature to create a barrier so that it can clean within a particular area. The Roomba uses spiraling, room crossing, dirt detection, and wall following techniques to calculate the best cleaning path. The Roomba series of robotic cleaners have changed the way floors are vacuumed. The Roomba is one of the most successful household robots, with almost a million units sold.