Let the Samsung Navibot SR8825 Red Robot Vacuum do your housework whilst you're out! Simply set the delayed start to clean after you've left & he will go off clean until he runs out of battery. As he is nearing exhaustion he takes himself back to his charging station to recharge. Once he's full charged he goes back to where he finished & continues cleaning! For an explanation of the differences between each model please see the bottom of this section. The main differences between the Navibot models are: The Red SR8825 has no virtual guards so you although it won't fall down the stairs you cannot prevent it going through an open doorway & no programming function so you have to use delayed start to clean whilst you are out The Blue SR8855 has daily scheduling & 2 virtual guards The Grey SR8895 has daily scheduling, only 1 virtual guard but is quieter than the red & blues at 62db rather than 73db. The Black SR8980 has daily scheduling & 2 virtual guards. It cleans faster covering 25sqm in 11 mins rather than the 18 minutes that the others take. It has 12 rather than 7 or 8 obstacle sensors like the other models. It also has 4 instead of 2 bumper guards. It cleans for a maximum of 100 minutes compared to 90 minutes on the other 3 models. But it takes longer to charge at 3 hours rather than 2. It is the quietest model @ 60db. It has a dust awareness system so it will clean the dirty areas more. Finally & most impressively the Black SR8980 will return to its charging station to empty its dust & debris into a 2L collection chamber so it can clean day after day without human intervention!