First off, instead of bashing them like others have, they do work, but not as well as a regular vacuum does. All the models return to their docking stations when they are done, or 25-45 mins have past (depending on the battery life).

As for the 500 sq foot room, I’d have to say the 400 model was only meant for a maximum of two 10×10 rooms, or one 10×25 room. The more time it must navigate the obstacles in its path, the more that will cut its battery usable charge.

My mum has one, and as a senior she loves the darling lil thing. lol She lets it run its route during the night when she is asleep and won’t trip over it during the day.

They do not work. Do not buy one, Get a regular vacuum instead and exert a little bit of muscle.