I chose this model 980, as I have an 870, which I like, and I needed another one for another home. I wanted something similar, without having to download an app on my phone to operate it, which is required on several newer models. Currently it is difficult to find new roomba 800 or 900 series, as they are discontinued by the brand, but I think that in aspects of "vacuuming", the most current ones have not advanced particularly. That's why I decided to go for a second-hand model, Roomba 980, which arrived on time, with original box in good condition and with all the accessories: charger and virtual doors, the latter still sealed, unused. The machine works perfectly. It has a lot of scratches on the upper perimeter. I was surprised, as I have my 870 and I have been using it for 10 years and it is not so scratched in that area. Surely where it was used before it coincided with some object that generated a lot of bumps in that area. But I didn't think it was important, as it doesn't affect its operation. Roomba 980 is similar to the 870. The 980 makes more noise, especially when it climbs on a carpet, as at that moment it automatically increases the suction power. This, on the other hand, is the main "advantage" of the 900 series over the 800, although with the disadvantage of noise and I suppose that this way of working with more power in carpet areas will damage the battery sooner. What I didn't like at all, and that's why I don't give it the maximum mark, is that the rubber rollers have not been replaced by new ones. They have a little yellow cover on one of the sides and the hairs get trapped there: THIS COVER CAN BE REMOVED AND CLEANED. The roomba 980 ones I received I don't think they had ever been removed, and the rubber rollers had lots of blonde hairs rolled up inside them, with the corresponding dirt, and I suppose their mites, and anything else that comes stuck to those hairs, which was unpleasant (I don't know if they were animal or human). I understand that this is not known to the person who inspects the roombas. Given that it is something that can be replaced, it seems more logical that new ones should always be put in, FOR HYGIENE. On the other hand, the roomba 980 can use the accessories of the 870 (charger, virtual doors, rollers, filter, brushes...).